[llvm] [CFIFixup] Precommit test ahead of multi-block prologues support (PR #72033)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Ah, feel free to just land this without review and rebase #68984  or use a merge

```
git switch pr1
git merge origin/main
git push $username pr1
```

(Rebasing a patch isn't an issue to me: https://maskray.me/blog/2023-09-09-reflections-on-llvm-switch-to-github-pull-requests#:~:text=another%20landed)

https://github.com/llvm/llvm-project/pull/72033