fix ldb_test TtlPutGet test
fix ldb_test TtlPutGet test

Summary:
If the last byte of the timestamp is 0, the output value of the ttl db
can cut off earlier. Change to compare hex format instead.

Test Plan:
this does not happen consistently, but it did not fail after the last
100 runs
for i in {1..100}; do python ./tools/ldb_test.py; done

Reviewers: igor, haobo

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16725

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