ctags and cscope support to Makefile
ctags and cscope support to Makefile

Summary: Added a target to Makefile called 'tags' that runs ctags and cscope on all *.cc and *.h file

Test Plan:
Run 'make tags'. Then start vim and do
:set tags=./tags
:cs add cscope.out

These commands should give you no error messages. You should then be able to access cscope db and ctags as normal in vim.

Reviewers: dhruba

Differential Revision: https://reviews.facebook.net/D11103

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