[clang] [Driver] Ensure ToolChain::LibraryPaths is not empty for non-Darwin (PR #87866)

[YunQiang Su via cfe-commits]

wzssyqa wrote:

For me, I think that it is a good idea to always warn/hint the full/normalized path.
For compatible reason, we can still try to find libraries in old-style or non-full/normalized paths, while should not hint them.

https://github.com/llvm/llvm-project/pull/87866