[CF] Fix column family dropping
[CF] Fix column family dropping

Summary: Column family should be dropped after the change has been commited

Test Plan: db stress

Reviewers: dhruba, haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16779

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