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

[Rahul Joshi via llvm-commits]

jurahul wrote:

I should have clarified it, and I have added it in the description now. It's adopting an existing LLVM coding standard rule in this file.

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