[Add randomwithverify benchmark option]
[Add randomwithverify benchmark option]

Summary: Added RandomWithVerify benchmark option.

Test Plan:
This whole diff is to test.
[nponnekanti@dev902 /data/users/nponnekanti/rocksdb] ./db_bench --benchmarks=randomwithverify
LevelDB:    version 1.5
Date:       Tue Feb 19 17:50:28 2013
CPU:        24 * Intel(R) Xeon(R) CPU           X5650  @ 2.67GHz
CPUCache:   12288 KB
Keys:       16 bytes each
Values:     100 bytes each (50 bytes after compression)
Entries:    1000000
RawSize:    110.6 MB (estimated)
FileSize:   62.9 MB (estimated)
Compression: snappy
WARNING: Assertions are enabled; benchmarks unnecessarily slow
------------------------------------------------
Created bg thread 0x7fa9c3fff700
randomwithverify :       5.004 micros/op 199836 ops/sec; ( get:900000 put:80000 del:20000 total:1000000 found:711992)

Revert Plan: OK

Task ID: #

Reviewers: dhruba, emayanke

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D8685

NickCis/rocksdb,anagav/rocksdb,RyanTech/rocksdb,bbiao/rocksdb,amyvmiwei/rocksdb,vashstorm/rocksdb,tsheasha/rocksdb,NickCis/rocksdb,msb-at-yahoo/rocksdb,jalexanderqed/rocksdb,norton/rocksdb,wlqGit/rocksdb,facebook/rocksdb,fengshao0907/rocksdb,luckywhu/rocksdb,wlqGit/rocksdb,JackLian/rocksdb,vashstorm/rocksdb,JoeWoo/rocksdb,siddhartharay007/rocksdb,mbarbon/rocksdb,anagav/rocksdb,vmx/rocksdb,facebook/rocksdb,virtdb/rocksdb,alihalabyah/rocksdb,hobinyoon/rocksdb,alihalabyah/rocksdb,tschottdorf/rocksdb,JackLian/rocksdb,bbiao/rocksdb,zhangpng/rocksdb,Vaisman/rocksdb,JackLian/rocksdb,msb-at-yahoo/rocksdb,siddhartharay007/rocksdb,rDSN-Projects/rocksdb.replicated,JoeWoo/rocksdb,facebook/rocksdb,ryneli/rocksdb,caijieming-baidu/rocksdb,rDSN-Projects/rocksdb.replicated,lgscofield/rocksdb,Vaisman/rocksdb,NickCis/rocksdb,tizzybec/rocksdb,alihalabyah/rocksdb,luckywhu/rocksdb,vmx/rocksdb,wenduo/rocksdb,siddhartharay007/rocksdb,Applied-Duality/rocksdb,msb-at-yahoo/rocksdb,SunguckLee/RocksDB,JoeWoo/rocksdb,Andymic/rocksdb,jalexanderqed/rocksdb,mbarbon/rocksdb,fengshao0907/rocksdb,bbiao/rocksdb,vmx/rocksdb,msb-at-yahoo/rocksdb,OverlordQ/rocksdb,SunguckLee/RocksDB,mbarbon/rocksdb,NickCis/rocksdb,temicai/rocksdb,Vaisman/rocksdb,biddyweb/rocksdb,Vaisman/rocksdb,wlqGit/rocksdb,Andymic/rocksdb,sorphi/rocksdb,NickCis/rocksdb,ryneli/rocksdb,caijieming-baidu/rocksdb,JoeWoo/rocksdb,tschottdorf/rocksdb,skunkwerks/rocksdb,OverlordQ/rocksdb,tizzybec/rocksdb,tizzybec/rocksdb,siddhartharay007/rocksdb,JoeWoo/rocksdb,RyanTech/rocksdb,temicai/rocksdb,biddyweb/rocksdb,tizzybec/rocksdb,virtdb/rocksdb,Andymic/rocksdb,virtdb/rocksdb,JackLian/rocksdb,flabby/rocksdb,OverlordQ/rocksdb,biddyweb/rocksdb,virtdb/rocksdb,amyvmiwei/rocksdb,tsheasha/rocksdb,fengshao0907/rocksdb,alihalabyah/rocksdb,skunkwerks/rocksdb,tsheasha/rocksdb,tschottdorf/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,wenduo/rocksdb,makelivedotnet/rocksdb,JohnPJenkins/rocksdb,jalexanderqed/rocksdb,wlqGit/rocksdb,caijieming-baidu/rocksdb,fengshao0907/rocksdb,makelivedotnet/rocksdb,lgscofield/rocksdb,jalexanderqed/rocksdb,jalexanderqed/rocksdb,ylong/rocksdb,norton/rocksdb,amyvmiwei/rocksdb,zhangpng/rocksdb,Andymic/rocksdb,zhangpng/rocksdb,OverlordQ/rocksdb,temicai/rocksdb,dkorolev/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,ryneli/rocksdb,NickCis/rocksdb,luckywhu/rocksdb,OverlordQ/rocksdb,tizzybec/rocksdb,lgscofield/rocksdb,rDSN-Projects/rocksdb.replicated,hobinyoon/rocksdb,temicai/rocksdb,alihalabyah/rocksdb,geraldoandradee/rocksdb,wlqGit/rocksdb,virtdb/rocksdb,OverlordQ/rocksdb,tsheasha/rocksdb,siddhartharay007/rocksdb,lgscofield/rocksdb,SunguckLee/RocksDB,wskplho/rocksdb,luckywhu/rocksdb,IMCG/RcoksDB,Vaisman/rocksdb,dkorolev/rocksdb,Applied-Duality/rocksdb,wat-ze-hex/rocksdb,wskplho/rocksdb,dkorolev/rocksdb,facebook/rocksdb,ylong/rocksdb,wenduo/rocksdb,vashstorm/rocksdb,norton/rocksdb,caijieming-baidu/rocksdb,IMCG/RcoksDB,wlqGit/rocksdb,Applied-Duality/rocksdb,IMCG/RcoksDB,wskplho/rocksdb,norton/rocksdb,sorphi/rocksdb,luckywhu/rocksdb,tsheasha/rocksdb,jalexanderqed/rocksdb,Vaisman/rocksdb,luckywhu/rocksdb,tizzybec/rocksdb,wenduo/rocksdb,wenduo/rocksdb,makelivedotnet/rocksdb,sorphi/rocksdb,NickCis/rocksdb,facebook/rocksdb,zhangpng/rocksdb,geraldoandradee/rocksdb,anagav/rocksdb,anagav/rocksdb,flabby/rocksdb,kaschaeffer/rocksdb,rDSN-Projects/rocksdb.replicated,OverlordQ/rocksdb,ylong/rocksdb,flabby/rocksdb,SunguckLee/RocksDB,Vaisman/rocksdb,geraldoandradee/rocksdb,norton/rocksdb,ylong/rocksdb,dkorolev/rocksdb,fengshao0907/rocksdb,skunkwerks/rocksdb,skunkwerks/rocksdb,wenduo/rocksdb,RyanTech/rocksdb,flabby/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,tsheasha/rocksdb,wat-ze-hex/rocksdb,zhangpng/rocksdb,norton/rocksdb,temicai/rocksdb,makelivedotnet/rocksdb,biddyweb/rocksdb,kaschaeffer/rocksdb,vashstorm/rocksdb,JohnPJenkins/rocksdb,norton/rocksdb,kaschaeffer/rocksdb,luckywhu/rocksdb,JohnPJenkins/rocksdb,wat-ze-hex/rocksdb,mbarbon/rocksdb,RyanTech/rocksdb,dkorolev/rocksdb,ryneli/rocksdb,ryneli/rocksdb,alihalabyah/rocksdb,anagav/rocksdb,JohnPJenkins/rocksdb,JohnPJenkins/rocksdb,facebook/rocksdb,biddyweb/rocksdb,wenduo/rocksdb,JackLian/rocksdb,geraldoandradee/rocksdb,zhangpng/rocksdb,facebook/rocksdb,temicai/rocksdb,wlqGit/rocksdb,makelivedotnet/rocksdb,dkorolev/rocksdb,caijieming-baidu/rocksdb,sorphi/rocksdb,virtdb/rocksdb,norton/rocksdb,mbarbon/rocksdb,JackLian/rocksdb,siddhartharay007/rocksdb,fengshao0907/rocksdb,tsheasha/rocksdb,msb-at-yahoo/rocksdb,rDSN-Projects/rocksdb.replicated,JohnPJenkins/rocksdb,IMCG/RcoksDB,hobinyoon/rocksdb,lgscofield/rocksdb,makelivedotnet/rocksdb,Applied-Duality/rocksdb,Andymic/rocksdb,IMCG/RcoksDB,JackLian/rocksdb,skunkwerks/rocksdb,rDSN-Projects/rocksdb.replicated,tschottdorf/rocksdb,caijieming-baidu/rocksdb,lgscofield/rocksdb,SunguckLee/RocksDB,JoeWoo/rocksdb,mbarbon/rocksdb,geraldoandradee/rocksdb,hobinyoon/rocksdb,amyvmiwei/rocksdb,rDSN-Projects/rocksdb.replicated,vashstorm/rocksdb,SunguckLee/RocksDB,msb-at-yahoo/rocksdb,biddyweb/rocksdb,RyanTech/rocksdb,vmx/rocksdb,tsheasha/rocksdb,tizzybec/rocksdb,geraldoandradee/rocksdb,JohnPJenkins/rocksdb,JoeWoo/rocksdb,amyvmiwei/rocksdb,kaschaeffer/rocksdb,ylong/rocksdb,vashstorm/rocksdb,sorphi/rocksdb,wskplho/rocksdb,bbiao/rocksdb,Andymic/rocksdb,IMCG/RcoksDB,biddyweb/rocksdb,alihalabyah/rocksdb,sorphi/rocksdb,bbiao/rocksdb,Applied-Duality/rocksdb,anagav/rocksdb,wskplho/rocksdb,bbiao/rocksdb,ylong/rocksdb,tschottdorf/rocksdb,tschottdorf/rocksdb,kaschaeffer/rocksdb,kaschaeffer/rocksdb,makelivedotnet/rocksdb,fengshao0907/rocksdb,ryneli/rocksdb,wat-ze-hex/rocksdb,skunkwerks/rocksdb,zhangpng/rocksdb,virtdb/rocksdb,Andymic/rocksdb,temicai/rocksdb,bbiao/rocksdb,dkorolev/rocksdb,facebook/rocksdb,IMCG/RcoksDB,amyvmiwei/rocksdb,hobinyoon/rocksdb,hobinyoon/rocksdb,flabby/rocksdb,Andymic/rocksdb,ryneli/rocksdb,hobinyoon/rocksdb,hobinyoon/rocksdb,siddhartharay007/rocksdb,wat-ze-hex/rocksdb,amyvmiwei/rocksdb,flabby/rocksdb,jalexanderqed/rocksdb,vashstorm/rocksdb,vmx/rocksdb,flabby/rocksdb,skunkwerks/rocksdb,geraldoandradee/rocksdb,ylong/rocksdb,wskplho/rocksdb,vmx/rocksdb,caijieming-baidu/rocksdb,vmx/rocksdb,mbarbon/rocksdb,wenduo/rocksdb,RyanTech/rocksdb,lgscofield/rocksdb,wat-ze-hex/rocksdb,Applied-Duality/rocksdb,sorphi/rocksdb,wskplho/rocksdb,kaschaeffer/rocksdb,anagav/rocksdb,Applied-Duality/rocksdb,RyanTech/rocksdb