[llvm] [MachO] Preserve weak linkage for aliases (PR #198148)

[Folkert de Vries via llvm-commits]

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

LGTM

Let's wait a couple more days for if the other reviewers do want to respond. Then, we'll see if the build bots find anything, and if not I propose we cherry-pick this into LLVM 23, given that it's an important fix and unblocks a bunch of development on the rust side.

https://github.com/llvm/llvm-project/pull/198148