Fix Travis on Mac
Fix Travis on Mac

Summary: not sure why travis complain about this line, works fine on my mac

Test Plan: run on my mac

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D63045

facebook/rocksdb,Andymic/rocksdb,norton/rocksdb,wat-ze-hex/rocksdb,tsheasha/rocksdb,Andymic/rocksdb,vmx/rocksdb,wenduo/rocksdb,Andymic/rocksdb,norton/rocksdb,vmx/rocksdb,bbiao/rocksdb,OverlordQ/rocksdb,SunguckLee/RocksDB,norton/rocksdb,tsheasha/rocksdb,facebook/rocksdb,norton/rocksdb,facebook/rocksdb,vmx/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,wenduo/rocksdb,SunguckLee/RocksDB,tsheasha/rocksdb,wenduo/rocksdb,bbiao/rocksdb,facebook/rocksdb,OverlordQ/rocksdb,tsheasha/rocksdb,norton/rocksdb,facebook/rocksdb,wenduo/rocksdb,vmx/rocksdb,OverlordQ/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,bbiao/rocksdb,norton/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,OverlordQ/rocksdb,wenduo/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,tsheasha/rocksdb,bbiao/rocksdb,OverlordQ/rocksdb,SunguckLee/RocksDB,OverlordQ/rocksdb,Andymic/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,norton/rocksdb,facebook/rocksdb,wat-ze-hex/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,vmx/rocksdb,bbiao/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,wat-ze-hex/rocksdb,wenduo/rocksdb,tsheasha/rocksdb,facebook/rocksdb,wenduo/rocksdb,OverlordQ/rocksdb,wat-ze-hex/rocksdb,norton/rocksdb,tsheasha/rocksdb,vmx/rocksdb,tsheasha/rocksdb,facebook/rocksdb,Andymic/rocksdb,wenduo/rocksdb,vmx/rocksdb