Fix mis-reporting of compaction read bytes to the base level
Fix mis-reporting of compaction read bytes to the base level

Summary:
In dynamic leveled compaction, when calculating read bytes, output level bytes may be wronglyl calculated as input level inputs. Fix it.
Closes https://github.com/facebook/rocksdb/pull/1475

Differential Revision: D4148412

Pulled By: siying

fbshipit-source-id: f2f475a

wat-ze-hex/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,bbiao/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,Andymic/rocksdb,vmx/rocksdb,bbiao/rocksdb,bbiao/rocksdb,bbiao/rocksdb,vmx/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,vmx/rocksdb,Andymic/rocksdb,bbiao/rocksdb,Andymic/rocksdb,vmx/rocksdb,Andymic/rocksdb,bbiao/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,vmx/rocksdb