Fixed compile errors (signed / unsigned comparison) in cuckoo_table_db_test on Mac
Fixed compile errors (signed / unsigned comparison) in cuckoo_table_db_test on Mac

Summary:
Fixed compile errors (signed / unsigned comparison) in cuckoo_table_db_test on Mac

Test Plan:
make cuckoo_table_db_test

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