Fix the valgrind error
Fix the valgrind error

Summary: I this bug from valgrind report and found a place that may potentially leak memory.

Test Plan: re-ran the valgrind and no error any more

Reviewers: emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D13959

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