[llvm] [Support][Windows] Use the original path if GetFinalPathNameByHandleW() failed (PR #87749)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo approved this pull request.

This change looks reasonable to me, but I want to loop in @aganea before landing it.

https://github.com/llvm/llvm-project/pull/87749