[clang-tools-extra] r196474 - Re-apply r196439, with sed patterns modified to be more DOS-path friendly.

[NAKAMURA Takumi]

> Note: I am not seeing this broken in MSVC 12 on Windows, so it may be
> mingw specific.

I wonder why you didn't reproduce the issue on your build tree!
It'd be win32 generic due to driveletter.

...or, I suspect you didn't enable clang-tools-extra...