[clang] [clang-format] convert path to Windows path if user is using a MSYS2 shell (PR #111526)

[Gary Wang via cfe-commits]

BLumia wrote:

> > Isn't this a Python/MSYS2 bug?
> 
> I'm not sure if it should be considered as a MSYS2 bug.

I also created a discussion thread, see: https://github.com/msys2/MSYS2-packages/discussions/4982


https://github.com/llvm/llvm-project/pull/111526