Summary:
Replace Status with IOStatus in CopyFile and CreateFile.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6916
Test Plan: pass make asan_check
Reviewed By: cheng-chang
Differential Revision: D21843775
Pulled By: zhichao-cao
fbshipit-source-id: 524d4a0fcf47f0941b923da0346e0de71607f5f6