[clang] [llvm] [clang][deps] Overload `Filesystem::exists` in `DependencyScanningFilesystem` to have it use cached `status` (PR #88152)

[Alexandre Ganea via cfe-commits]

https://github.com/aganea commented:

Thanks for the change! Quite interestingly I was just looking precisely at this issue today :smile: Things are worst on Windows, where mini-filter drivers kick-in and bring performance to its knees. I'll try your patch, see how that improves my usage!

<img width="1920" alt="image" src="https://github.com/llvm/llvm-project/assets/37383324/f6fc28e2-8039-4cfc-aaa8-bfbbfe234394">


https://github.com/llvm/llvm-project/pull/88152