[libcxx-commits] [libcxxabi] [llvm] [ItaniumDemangle][test] Factor demangler test-cases into file and sync into LLVM (PR #137947)

[Louis Dionne via libcxx-commits]

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

LGTM, thanks!

As a follow-up, could you check whether it would make sense to update the test added in #140323 to ensure that the test data stays synchronized as well? I don't want to delay this patch further so I think it's fine doing as a follow-up.

https://github.com/llvm/llvm-project/pull/137947