[clang] [llvm] Introduce -funique-source-file-names flag. (PR #135728)

[Peter Collingbourne via cfe-commits]

pcc wrote:

> Is the "name" in this context the whole path? Or just the filename? I know many projects have files with the same name in different folders (including LLVM itsef).

It is the whole path. Let me clarify this in the documentation.

https://github.com/llvm/llvm-project/pull/135728