[clang] [clang][flang][windows] Prefer user-provided library paths (-L) (PR #90758)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space approved this pull request.

LGTM, thanks!

I've left some nits, feel free to ignore

https://github.com/llvm/llvm-project/pull/90758