[llvm] [LTT] Mark as unkown weak function tests. (PR #167399)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

### Merge activity

* **Nov 19, 12:51 AM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.com/github/pr/llvm/llvm-project/167399).


https://github.com/llvm/llvm-project/pull/167399