Fix a bug in GetApproximateSizes
Fix a bug in GetApproximateSizes

Summary: Need to pass through the memtable parameter.

Test Plan: built, tested through myrocks

Reviewers: igor, sdong, rven

Reviewed By: rven

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D49167

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