Add aof_rewrite_buffer_length INFO field.
Add aof_rewrite_buffer_length INFO field.

The INFO output, persistence section, already contained the field
describing the size of the current AOF buffer to flush on disk. However
the other AOF buffer, used to accumulate changes during an AOF rewrite,
was not mentioned in the INFO output.

This commit introduces a new field called aof_rewrite_buffer_length with
the length of the rewrite buffer.

takeshineshiro/redis,universsky/redis,cusspvz/redis,sunlianqiang/redis-3.0-annotated,ctripcorp/redis,iandyh/redis,huangz1990/redis-3.0-annotated,huangz1990/experiment-redis,pietern/redis,charsyam/redis,antirez/redis,ctripcorp/redis,iandyh/redis,twskipper/redis,takeshineshiro/redis,zhoudayang/redis,ttuna/msot-redis,roth1002/redis,MasahikoSawada/redis,gspandy/annotated_redis_source,badboy/redis,xuzhezhaozhao/redis_reading,jingjidejuren/redis,PKRoma/redis,fengshao0907/annotated_redis_source,qiyang0221/redis,josiahcarlson/redis,janekmi/redis,oranagra/redis,narma/redis,netroby/redis,mumingv/redis-3.0-annotated,mengzhejin/RedisStudy,JoeWoo/redis,csuhawk/redis,jbochi/redis,pietern/redis,hornen/redis,ouyangkongtong/redis,magastzheng/redis-3.0-annotated,0x20h/redis,gechong/redis-3.0-annotated,izhoujie/redis,ncopa/redis,timothyohare/3rdPartySrc-redis,zhoudayang/redis,colstrom/redis,citusdata/redis,j0hnma/hszredis,wprice/redis,davidradunz/redis,Soledad89/redis,WorkingOfTimtohyZhang/redis-3.0-annotated,elkingtonmcb/redis,gilala/bjredis,figoxu/annotated_redis_source,gongice/redis-3.0-annotated,abhiklodh/redis,WorkingOfTimtohyZhang/redis-3.0-annotated,vincent-vivian-liu/redis,mengyou0304/redis,hornen/redis,nilyang/redis-tdd-annotation,ipmobiletech/redis,tzq668766/redis-3.0-annotated,huangz1990/annotated_redis_source,fengshao0907/redis,weizijun/redis,gaoxianglong/redis,dayuoba/redis,hawkchch/redis,ReadCode/redis-3.0-annotated,huangz1990/annotated_redis_source,shshlzh/redis-3.0-annotated,wuxiaowei907/annotated_redis_source,zczhuohuo/redis,izhoujie/redis,PradheepShrinivasan/redis,ketor/redis,rouzier/redis,ttuna/msot-redis,pkdevbox/redis,yybirdcf/learn-redis,mengzhejin/RedisStudy,wbailey5/redis,Aliceljm1/redis,h0x91b/redis,Sciumo/redis,hedisdb/hedis,supasate/redis,roth1002/redis,izhoujie/redis,itamarhaber/redis,ytjiang/redis,seandsky/redis,pcarrier/redis,Markgorden/redis,elkingtonmcb/redis,adamweixuan/redis-3.0-annotated,ChaosCoo/annotated_redis_source,abhiklodh/redis,jbochi/parallel_redis,Cisphyx/redis-websockets,AplayER/redis,slfs007/mk-redis,ttuna/msot-redis,Cisphyx/redis-websockets,dramenk/annotated_redis_source,netroby/redis,ofirluzon/redis,zguangyu/redis,july2993/redis,kensou97/redis,aim-for-better/redis,badboy/redis,seppo0010/rlite-server,soveran/redis,pkdevbox/redis,ksarch-saas/redis,xuzhezhaozhao/redis_reading,spearhead-ea/redis,francischan714/redis,takeshineshiro/redis,yybirdcf/learn-redis,nilyang/redis-tdd-annotation,mrb/redis,zhiliaoniu/redis,netroby/redis,OmarQunsul/graph-redis,machicao2013/redis-source-annotated,tjschuck/redis,honestme/redis,LongXQ/redis,aluzzardi/redis,viongpanzi/annotated_redis_source,guker/redis,zhaobo1023/redis-3.0-annotated,francischan714/redis,onlymellb/redis-3.0-annotated,citusdata/redis,xuzhezhaozhao/redis_reading,netroby/redis,gilala/hbjredis,Aliceljm1/redis-3.0-annotated,4396/redis,rouzier/redis,zhiliaoniu/redis,guker/redis,mcanthony/redis,GitHubMota/redis,allengaller/redis,yuhc/redis-benchmark-enhanced,ChaosCoo/annotated_redis_source,louisliangjun/redis,YuanZhewei/redis,yuhc/redis-benchmark-enhanced,AplayER/redis,pcarrier/redis,linfangrong/redis,valdsJohn/redis,MSOpenTech/redis,z-fork/redis,kmiku7/redis,blackmady/redis,ituncle/redis,YuraLukashik/redis,atreeyang/redis,cusspvz/redis,duanx/redis,yossigo/redis,cloudrain21/redis,aim-for-better/redis,JoeWoo/redis,rrsean/redis-3.0-annotated,figoxu/annotated_redis_source,sunheehnus/redis,vincent-vivian-liu/redis,spinlock/redis,Aliceljm1/redis,LongXQ/redis,moonbingbing/redis-3.0-annotated,ramonsnir/redis,himoca/redis,charsyam/redis,4396/redis,wangyikai/redis,tanghaodong25/redis,0x20h/redis,cusspvz/redis,alenslan/redis,maodeyi/redis_lua,universsky/redis,AALEKH/redis,riyan8250/redis,huangz1990/experiment-redis,nuxeh/redis,jasonkying/redis,harrisonfeng/redis,universsky/redis,mpalmer/redis,spinlock/redis,drinkthere/redis-3.0-annotated,rogerchina/redis,danny200309/annotated_redis_source,darksideofthemoo/redis-histogram,pedigree/redis,july2993/redis,MSOpenTech/redis,ErikDubbelboer/redis,zczhuohuo/redis,alenslan/redis,thomasdarimont/redis,louisliangjun/redis,wujf/redis,qiyang0221/redis,Aliceljm1/redis,josephholsten/redis,kensou97/redis,louisliangjun/redis,yybirdcf/learn-redis,j0hnma/hszredis,simplestbest/redis,h0x91b/redis,ofirluzon/redis,weizijun/redis,clamoriniere1A/redis,SummonY/redis,narma/redis,LongXQ/redis,oranagra/redis,vincent-vivian-liu/redis,zhaobo1023/redis-3.0-annotated,clamoriniere1A/redis,hhli/redis,gaoxianglong/redis,narma/redis,seppo0010/rlite-server,huangz1990/experiment-redis,huangz1990/redis-3.0-annotated,soveran/redis,neomantra/redis,citusdata/redis,ton31337/redis,Markgorden/redis,himoca/redis,YuanZhewei/redis,dayuoba/redis,yossigo/redis,mumingv/redis,spinlock/redis,flashbuckets/redis,josephholsten/redis,SummonY/redis,july2993/redis,spearhead-ea/redis,Wangyao14cyy/redis,roth1002/redis,seppo0010/rlite-server,arijitvt/redis,pietern/redis,adamweixuan/redis-3.0-annotated,pmem/redis,xlzhan/redis,timothyohare/3rdPartySrc-redis,fengshao0907/redis,MSOpenTech/redis,antirez/redis,sunheehnus/redis,kaushik94/redis,zhoudayang/redis,thomasdarimont/redis,supasate/redis,cnbin/redis,mingyaaaa/redis,seppo0010/redis,haima-zju/redis-3.0-annotated,honestme/redis,csuhawk/redis,colstrom/redis,modulexcite/redis,taoguan/redis,SummonY/redis,dayuoba/redis,dreamquster/redis,itamarhaber/redis,yossigo/redis,kmiku7/redis,Aliceljm1/redis-3.0-annotated,hhli/redis,duanx/redis,zhcy/redis,wuyu201321060203/redis-3.0-annotated,YuraLukashik/redis,a-pavlov/redis,ReadCode/redis-3.0-annotated,ErikDubbelboer/redis,programmecat/redis,maodeyi/redis_lua,z-fork/redis,JoeWoo/redis,zhcy/redis,jxwr/redis,yossigo/redis,SummonY/redis,ncopa/redis,izhoujie/redis,itugs/redis,neomantra/redis,dreamquster/redis,ofirluzon/redis,sunlianqiang/redis-3.0-annotated,ChaosCoo/annotated_redis_source,miaoyc1989/redis-3.0-annotated,zguangyu/redis,taoguan/redis,ramonsnir/redis,moonbingbing/redis-3.0-annotated,thomasdarimont/redis,valdsJohn/redis,wujf/redis,buobao/redis-3.0-annotated,0x55/redis-3.0-annotated,xujunhai1991/redis,Sciumo/redis,dongqifan2/redis-3.0-annotated,drinkthere/redis-3.0-annotated,abhiklodh/redis,spearhead-ea/redis,gilala/hredis,atreeyang/redis,gilala/hredis,cusspvz/redis,flashbuckets/redis,valdsJohn/redis,gilala/redis,dramenk/annotated_redis_source,shshlzh/redis-3.0-annotated,pedigree/redis,linfangrong/redis,wprice/redis,haima-zju/redis-3.0-annotated,gspandy/annotated_redis_source,tellapart/redis,tanghaodong25/redis,wenxueliu/redis_comment,zguangyu/redis,wujf/redis,huangz1990/experiment-redis,xuzhezhaozhao/redis_reading,brg-liuwei/redis,CodeJuan/redis,saisai/redis,idning/redis,GitHubMota/redis,msn217/redis-3.0-annotated,badboy/redis,itugs/redis,zhcy/redis,neomantra/redis,soloestoy/redis,tjschuck/redis,harrisonfeng/redis,SyntaxStacks/redis,kaushik94/redis,whille/redis-3.0-annotated,mumingv/redis-3.0-annotated,seandsky/redis,francischan714/redis,mcanthony/redis,GitHubMota/redis,antirez/redis,pietern/redis,josephholsten/redis,AplayER/redis,jacklee0810/redis-3.0-annotated,ksarch-saas/redis,MasahikoSawada/redis,0x55/redis-3.0-annotated,pkdevbox/redis,magastzheng/redis-3.0-annotated,yuhc/redis-benchmark-enhanced,MSOpenTech/redis,Aaron1992/redis,shshlzh/redis-3.0-annotated,dongqifan2/redis-3.0-annotated,jingjidejuren/redis,josiahcarlson/redis,ituncle/redis,rogerchina/redis,gspandy/annotated_redis_source,charsyam/redis,slfs007/mk-redis,msn217/redis-3.0-annotated,dreamquster/redis,StevenTsai/redis,GrimDerp/redis,huyuezheng/redis,darksideofthemoo/redis-histogram,blackmady/redis,wangyikai/redis,pmem/redis,NBSW/redis,nnog/redis,rouzier/redis,supasate/redis,z-fork/redis,Aliceljm1/redis-3.0-annotated,jacklee0810/annotated_redis_source,Markgorden/redis,CodeJuan/redis,mpalmer/redis,idning/redis,oranagra/redis,mverrilli/redis,zhoudayang/redis,0x55/redis-3.0-annotated,dramenk/annotated_redis_source,AALEKH/redis,gilala/redis,jacklee0810/redis-3.0-annotated,OmarQunsul/graph-redis,mumingv/redis,danny200309/annotated_redis_source,hedisdb/hedis,splitice/redis,charsyam/redis,timothyohare/3rdPartySrc-redis,ouyangkongtong/redis,PKRoma/redis,rrsean/redis-3.0-annotated,holstvoogd/redis,ChanningDuan/annotated_redis_source,shining-yang/redis,buobao/redis-3.0-annotated,YongMan/redis,yossigo/redis,duanx/redis,rogerchina/redis,fengshao0907/redis,rrsean/redis-3.0-annotated,shreesundara/redis,colstrom/redis,jacklee0810/annotated_redis_source,cloudrain21/redis,OmarQunsul/graph-redis,wenxueliu/redis_comment,HouKangkang/redis-3.0-annotated,rogerlz/redis,SyntaxStacks/redis,xujunhai1991/redis,RepmujNetsik/redis,jackyan/redis,PradheepShrinivasan/redis,PradheepShrinivasan/redis,mgk/redis,itamarhaber/redis,Sciumo/redis,fengshao0907/annotated_redis_source,PradheepShrinivasan/redis,csuhawk/redis,gilala/bjredis,shreesundara/redis,onlymellb/redis-3.0-annotated,fengshao0907/redis-3.0-annotated,jasonkying/redis,pcarrier/redis,zhaobo1023/redis-3.0-annotated,moonbingbing/redis-3.0-annotated,mingyaaaa/redis,pcarrier/redis,programmecat/redis,simplestbest/redis,janekmi/redis,itugs/redis,a-pavlov/redis,PKRoma/redis,jacklee0810/redis-3.0-annotated,magastzheng/redis-3.0-annotated,healerkx/redis,mcanthony/redis,dreamquster/redis,jbochi/parallel_redis,vincent-vivian-liu/redis,pedigree/redis,taoguan/redis,ipmobiletech/redis,jermnelson/redis,xujunhai1991/redis,splitice/redis,arijitvt/redis,a-pavlov/redis,aluzzardi/redis,brg-liuwei/redis,pmem/redis,tellapart/redis,twskipper/redis,zy416548283/redis-3.0-annotated,ncopa/redis,rogerlz/redis,figoxu/annotated_redis_source,jackyan/redis,blackmady/redis,elkingtonmcb/redis,linfangrong/redis,fankeke/redis-3.0-annotated,tzq668766/redis-3.0-annotated,GrimDerp/redis,nuxeh/redis,janekmi/redis,gilala/hredis,0x20h/redis,mgk/redis,a-pavlov/redis,YongMan/redis,huangz1990/annotated_redis_source,Markgorden/redis,modulexcite/redis,cnbin/redis,gilala/hredis,Soledad89/redis,tidatida/annotated_redis_source,mcanthony/redis,fengshao0907/redis,allengaller/redis,jbochi/redis,xuguruogu/redis,cnbin/redis,GrimDerp/redis,xuguruogu/redis,gechong/redis-3.0-annotated,huyuezheng/redis,gechong/redis-3.0-annotated,Hailei/redis,maodeyi/redis_lua,j0hnma/szredis,mengyou0304/redis,programmecat/redis,hedisdb/hedis,iandyh/redis,idning/redis,csuhawk/redis,Hailei/redis,arijitvt/redis,ipmobiletech/redis,holstvoogd/redis,mumingv/redis,riyan8250/redis,190235047/redis,mverrilli/redis,janekmi/redis,wprice/redis,machicao2013/redis-source-annotated,gaoxianglong/redis,Wangyao14cyy/redis,Aaron1992/redis,hornen/redis,programmecat/redis,saisai/redis,4396/redis,roth1002/redis,ofirluzon/redis,YuraLukashik/redis,abhiklodh/redis,h0x91b/redis,pedigree/redis,unasm/redis-3.0-annotated,GrimDerp/redis,guker/redis,unasm/redis-3.0-annotated,colstrom/redis,seppo0010/redis,soloestoy/redis,jermnelson/redis,MasahikoSawada/redis,ttuna/msot-redis,4396/redis,fengshao0907/redis-3.0-annotated,nnog/redis,ErikDubbelboer/redis,NBSW/redis,wuyu201321060203/redis-3.0-annotated,splitice/redis,mrb/redis,valdsJohn/redis,huangz1990/redis-3.0-annotated,jingjidejuren/redis,mgk/redis,HeartSaVioR/redis,hornen/redis,gilala/bjredis,whille/redis-3.0-annotated,hhli/redis,cnbin/redis,zczhuohuo/redis,gilala/hbjredis,mverrilli/redis,ChanningDuan/annotated_redis_source,itamarhaber/redis,danny200309/annotated_redis_source,soloestoy/redis,shining-yang/redis,ipmobiletech/redis,gaoxianglong/redis,wbailey5/redis,hhli/redis,mattsta/redis,MSOpenTech/redis,xlzhan/redis,pkdevbox/redis,takeshineshiro/redis,adamweixuan/redis-3.0-annotated,hedisdb/hedis,cloudrain21/redis,wujf/redis,oranagra/redis,ofirluzon/redis,ttuna/msot-redis,clamoriniere1A/redis,xujunhai1991/redis,tzq668766/redis-3.0-annotated,StevenTsai/redis,alenslan/redis,wbailey5/redis,zhcy/redis,zhiliaoniu/redis,zguangyu/redis,jxwr/redis,soloestoy/redis,ramonsnir/redis,mingyaaaa/redis,drinkthere/redis-3.0-annotated,YuanZhewei/redis,qiyang0221/redis,weizijun/redis,z-fork/redis,j0hnma/hszredis,hgl888/redis,mgk/redis,devaos/redis,universsky/redis,ChanningDuan/annotated_redis_source,mengzhejin/RedisStudy,nilyang/redis-tdd-annotation,sunlianqiang/redis-3.0-annotated,huyuezheng/redis,StevenTsai/redis,gilala/redis,tjschuck/redis,harrisonfeng/redis,RepmujNetsik/redis,j0hnma/szredis,linfangrong/redis,honestme/redis,haima-zju/redis-3.0-annotated,modulexcite/redis,jacklee0810/annotated_redis_source,wuxiaowei907/annotated_redis_source,hgl888/redis,healerkx/redis,190235047/redis,LongXQ/redis,kensou97/redis,thomasdarimont/redis,onlymellb/redis-3.0-annotated,blackmady/redis,xuguruogu/redis,josiahcarlson/redis,OmarQunsul/graph-redis,RepmujNetsik/redis,ksarch-saas/redis,ton31337/redis,yybirdcf/learn-redis,gongice/redis-3.0-annotated,StevenTsai/redis,190235047/redis,dayuoba/redis,wuyu201321060203/redis-3.0-annotated,gilala/hbjredis,SyntaxStacks/redis,soloestoy/redis,0x55/redis-3.0-annotated,ketor/redis,ytjiang/redis,ton31337/redis,devaos/redis,weizijun/redis,GitHubMota/redis,Cisphyx/redis-websockets,tjschuck/redis,jasonkying/redis,wangyikai/redis,miaoyc1989/redis-3.0-annotated,machicao2013/redis-source-annotated,badboy/redis,jackyan/redis,atreeyang/redis,soveran/redis,taoguan/redis,twskipper/redis,guker/redis,simplestbest/redis,fengshao0907/redis-3.0-annotated,simplestbest/redis,nilyang/redis-tdd-annotation,Wangyao14cyy/redis,zy416548283/redis-3.0-annotated,neomantra/redis,oranagra/redis,rouzier/redis,wenxueliu/redis_comment,brg-liuwei/redis,MOON-CLJ/redis,healerkx/redis,arijitvt/redis,jermnelson/redis,j0hnma/szredis,HunanTV/redis,brg-liuwei/redis,yuzhangjob/redis-3.0-annotated-unstable,jasonkying/redis,Aaron1992/redis,splitice/redis,jbochi/redis,NBSW/redis,mumingv/redis,tanghaodong25/redis,riyan8250/redis,duanx/redis,wangyikai/redis,saisai/redis,alenslan/redis,ncopa/redis,harrisonfeng/redis,SyntaxStacks/redis,ouyangkongtong/redis,ton31337/redis,mattsta/redis,rogerchina/redis,Aaron1992/redis,gilala/hbjredis,tellapart/redis,allengaller/redis,MOON-CLJ/redis,hawkchch/redis,himoca/redis,nuxeh/redis,buobao/redis-3.0-annotated,machicao2013/redis-source-annotated,HeartSaVioR/redis,gilala/bjredis,wenxueliu/redis_comment,ituncle/redis,healerkx/redis,RepmujNetsik/redis,honestme/redis,clamoriniere1A/redis,ytjiang/redis,dongqifan2/redis-3.0-annotated,july2993/redis,HunanTV/redis,nuxeh/redis,Hailei/redis,seandsky/redis,riyan8250/redis,MasahikoSawada/redis,zhiliaoniu/redis,tellapart/redis,aluzzardi/redis,darksideofthemoo/redis-histogram,hawkchch/redis,mpalmer/redis,shining-yang/redis,rogerlz/redis,holstvoogd/redis,louisliangjun/redis,davidradunz/redis,spinlock/redis,jingjidejuren/redis,AplayER/redis,atreeyang/redis,Wangyao14cyy/redis,shshlzh/redis-3.0-annotated,hawkchch/redis,WorkingOfTimtohyZhang/redis-3.0-annotated,seppo0010/redis,YongMan/redis,viongpanzi/annotated_redis_source,aluzzardi/redis,NBSW/redis,CodeJuan/redis,miaoyc1989/redis-3.0-annotated,ketor/redis,PKRoma/redis,xlzhan/redis,wbailey5/redis,0x20h/redis,ErikDubbelboer/redis,sunheehnus/redis,PKRoma/redis,neomantra/redis,gongice/redis-3.0-annotated,jackyan/redis,AALEKH/redis,josiahcarlson/redis,miaoyc1989/redis-3.0-annotated,mrb/redis,fankeke/redis-3.0-annotated,ituncle/redis,Soledad89/redis,cloudrain21/redis,kmiku7/redis,Cisphyx/redis-websockets,YuraLukashik/redis,wuxiaowei907/annotated_redis_source,seandsky/redis,yuhc/redis-benchmark-enhanced,idning/redis,francischan714/redis,holstvoogd/redis,yuzhangjob/redis-3.0-annotated-unstable,iandyh/redis,rogerlz/redis,mpalmer/redis,YongMan/redis,gilala/redis,xuguruogu/redis,zy416548283/redis-3.0-annotated,kmiku7/redis,kensou97/redis,mrb/redis,supasate/redis,aim-for-better/redis,msn217/redis-3.0-annotated,flashbuckets/redis,mingyaaaa/redis,mumingv/redis-3.0-annotated,mengyou0304/redis,HouKangkang/redis-3.0-annotated,saisai/redis,ytjiang/redis,seppo0010/rlite-server,unasm/redis-3.0-annotated,seppo0010/redis,MOON-CLJ/redis,AALEKH/redis,whille/redis-3.0-annotated,huyuezheng/redis,yuzhangjob/redis-3.0-annotated-unstable,Sciumo/redis,viongpanzi/annotated_redis_source,davidradunz/redis,Aliceljm1/redis,antirez/redis,elkingtonmcb/redis,mverrilli/redis,sunheehnus/redis,HeartSaVioR/redis,j0hnma/hszredis,modulexcite/redis,Soledad89/redis,kaushik94/redis,tanghaodong25/redis,pmem/redis,slfs007/mk-redis,citusdata/redis,Hailei/redis,itugs/redis,tidatida/annotated_redis_source,fengshao0907/annotated_redis_source,flashbuckets/redis,timothyohare/3rdPartySrc-redis,190235047/redis,hgl888/redis,CodeJuan/redis,ReadCode/redis-3.0-annotated,soveran/redis,darksideofthemoo/redis-histogram,mattsta/redis,HeartSaVioR/redis,devaos/redis,wuyu201321060203/redis-3.0-annotated,ctripcorp/redis,aim-for-better/redis,jbochi/parallel_redis,hgl888/redis,mengzhejin/RedisStudy,ksarch-saas/redis,YuanZhewei/redis,zczhuohuo/redis,shreesundara/redis,davidradunz/redis,jxwr/redis,nnog/redis,fankeke/redis-3.0-annotated,devaos/redis,mengyou0304/redis,xlzhan/redis,nnog/redis,tidatida/annotated_redis_source,HunanTV/redis,j0hnma/szredis,wprice/redis,twskipper/redis,qiyang0221/redis,charsyam/redis,ouyangkongtong/redis,JoeWoo/redis,shreesundara/redis,allengaller/redis,HouKangkang/redis-3.0-annotated,ctripcorp/redis,shining-yang/redis,HunanTV/redis,h0x91b/redis,kaushik94/redis