Summary:
`WritableFileWrapper` was missing some newer methods that were added to `WritableFile`. Without these functions, the missing wrapper methods would fallback to using the default implementations in WritableFile instead of using the corresponding implementations in, say, `PosixWritableFile` or `WinWritableFile`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4584
Differential Revision: D10559199
Pulled By: sagar0
fbshipit-source-id: 0d0f18a486aee727d5b8eebd3110a41988e27391