fix a warning in db_test when running `make release`
fix a warning in db_test when running `make release`

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