Fix the issue in PreShutdownMultipleCompaction
Fix the issue in PreShutdownMultipleCompaction

Summary: Fix the issue in PreShutdownMultipleCompaction

Test Plan:
export ROCKSDB_TESTS=PreShutdownMultipleCompaction
./db_test

Reviewers: rven, sdong, igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D35055

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