Fix clang build
Fix clang build

Summary: Fix clang

Test Plan: make check

Reviewers: sdong, yhchiang, rven

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D51417

bbiao/rocksdb,tsheasha/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,bbiao/rocksdb,Andymic/rocksdb,tsheasha/rocksdb,OverlordQ/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,vmx/rocksdb,norton/rocksdb,flabby/rocksdb,vmx/rocksdb,wenduo/rocksdb,norton/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,hobinyoon/rocksdb,bbiao/rocksdb,jalexanderqed/rocksdb,flabby/rocksdb,OverlordQ/rocksdb,hobinyoon/rocksdb,OverlordQ/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,tsheasha/rocksdb,Andymic/rocksdb,facebook/rocksdb,vmx/rocksdb,tsheasha/rocksdb,vmx/rocksdb,hobinyoon/rocksdb,Andymic/rocksdb,facebook/rocksdb,norton/rocksdb,wenduo/rocksdb,jalexanderqed/rocksdb,jalexanderqed/rocksdb,Vaisman/rocksdb,tsheasha/rocksdb,Andymic/rocksdb,Andymic/rocksdb,Vaisman/rocksdb,hobinyoon/rocksdb,wat-ze-hex/rocksdb,facebook/rocksdb,hobinyoon/rocksdb,facebook/rocksdb,ryneli/rocksdb,wat-ze-hex/rocksdb,jalexanderqed/rocksdb,SunguckLee/RocksDB,Vaisman/rocksdb,hobinyoon/rocksdb,jalexanderqed/rocksdb,bbiao/rocksdb,jalexanderqed/rocksdb,norton/rocksdb,OverlordQ/rocksdb,bbiao/rocksdb,bbiao/rocksdb,flabby/rocksdb,bbiao/rocksdb,vmx/rocksdb,facebook/rocksdb,ryneli/rocksdb,OverlordQ/rocksdb,ryneli/rocksdb,Vaisman/rocksdb,wenduo/rocksdb,SunguckLee/RocksDB,facebook/rocksdb,flabby/rocksdb,hobinyoon/rocksdb,vmx/rocksdb,wenduo/rocksdb,Andymic/rocksdb,tsheasha/rocksdb,norton/rocksdb,OverlordQ/rocksdb,flabby/rocksdb,facebook/rocksdb,ryneli/rocksdb,Vaisman/rocksdb,norton/rocksdb,tsheasha/rocksdb,wat-ze-hex/rocksdb,ryneli/rocksdb,SunguckLee/RocksDB,Vaisman/rocksdb,tsheasha/rocksdb,wenduo/rocksdb,norton/rocksdb,OverlordQ/rocksdb,vmx/rocksdb,facebook/rocksdb,ryneli/rocksdb,wenduo/rocksdb,wat-ze-hex/rocksdb,jalexanderqed/rocksdb,norton/rocksdb,vmx/rocksdb,hobinyoon/rocksdb,SunguckLee/RocksDB,flabby/rocksdb,wat-ze-hex/rocksdb,ryneli/rocksdb,wenduo/rocksdb,flabby/rocksdb,Vaisman/rocksdb,SunguckLee/RocksDB,wenduo/rocksdb