[llvm] [NFC][LLVM] Namespace cleanup in MSCVPaths (PR #163779)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> I don't see the reason for this change. The commit message also doesn't explain why this is being done. The use of the scoped `llvm` seems reasonable to me, and avoids unnecessary indentation.

This is one thing that LLVM style differs from Google style. Google's appears to rely on -Wmissing-declarations to catch misspelled definitions.

https://github.com/llvm/llvm-project/pull/163779