[clang-tools-extra] Re-add path normalization that was removed in 315561c86778 (PR #118718)

[Nicolas van Kempen via cfe-commits]

nicovank wrote:

I see, thanks for looking into it! To be honest I think `file_name_re` could be removed, `--source-filter` already takes in a regex and filters files based on it, which is more clear. The `files` arguments could just be taken as-is as a list of file paths (or maybe optionally directories to recurse). This sounds like it would fix this case (and it's closer to what the `clang-tidy` executable does) but maybe break others.

What do people think? @5chmidti @PiotrZSL @HerrCai0907 @carlosgalvezp?



https://github.com/llvm/llvm-project/pull/118718