[clang] [Driver] Some improvements for path handling on NetBSD (PR #66863)

[Brad Smith via cfe-commits]

brad0 wrote:

> This is similar to a change that I did for the Linux toolchain a while ago (https://github.com/llvm/llvm-project/commit/e917801eddbe1b32f1adc81391fd434557391b5e), LGTM! 👍

Thanks. I have been doing the same with other Drivers.

https://github.com/llvm/llvm-project/pull/66863