Revert "Use async file handle for better parallelism (#1049)" (#1105)
Revert "Use async file handle for better parallelism (#1049)" (#1105)

This reverts commit b54c34742412af0001a69c2f7d909bc05e1ea71f.

Revert async file handle change as it causes failures with appveyor
wat-ze-hex/rocksdb,Andymic/rocksdb,ryneli/rocksdb,Andymic/rocksdb,vmx/rocksdb,bbiao/rocksdb,facebook/rocksdb,ryneli/rocksdb,norton/rocksdb,jalexanderqed/rocksdb,wat-ze-hex/rocksdb,norton/rocksdb,ryneli/rocksdb,hobinyoon/rocksdb,facebook/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,wenduo/rocksdb,OverlordQ/rocksdb,facebook/rocksdb,jalexanderqed/rocksdb,SunguckLee/RocksDB,hobinyoon/rocksdb,hobinyoon/rocksdb,jalexanderqed/rocksdb,jalexanderqed/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,OverlordQ/rocksdb,norton/rocksdb,tsheasha/rocksdb,wat-ze-hex/rocksdb,wat-ze-hex/rocksdb,hobinyoon/rocksdb,hobinyoon/rocksdb,SunguckLee/RocksDB,norton/rocksdb,ryneli/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,wenduo/rocksdb,OverlordQ/rocksdb,jalexanderqed/rocksdb,SunguckLee/RocksDB,jalexanderqed/rocksdb,bbiao/rocksdb,norton/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,ryneli/rocksdb,OverlordQ/rocksdb,OverlordQ/rocksdb,Andymic/rocksdb,Andymic/rocksdb,vmx/rocksdb,ryneli/rocksdb,hobinyoon/rocksdb,tsheasha/rocksdb,wat-ze-hex/rocksdb,hobinyoon/rocksdb,vmx/rocksdb,bbiao/rocksdb,vmx/rocksdb,norton/rocksdb,facebook/rocksdb,wenduo/rocksdb,bbiao/rocksdb,wat-ze-hex/rocksdb,facebook/rocksdb,wenduo/rocksdb,tsheasha/rocksdb,tsheasha/rocksdb,hobinyoon/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,facebook/rocksdb,tsheasha/rocksdb,Andymic/rocksdb,facebook/rocksdb,Andymic/rocksdb,norton/rocksdb,OverlordQ/rocksdb,OverlordQ/rocksdb,Andymic/rocksdb,facebook/rocksdb,wenduo/rocksdb,vmx/rocksdb,bbiao/rocksdb,tsheasha/rocksdb,jalexanderqed/rocksdb,wenduo/rocksdb,vmx/rocksdb,wenduo/rocksdb,tsheasha/rocksdb,norton/rocksdb,wenduo/rocksdb,ryneli/rocksdb,tsheasha/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb