[llvm] [SimplfyCFG] Set `MD_prof` for `select` used for certain conditional simplifications (PR #154426)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

### Merge activity

* **Sep 12, 2:49 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/154426).


https://github.com/llvm/llvm-project/pull/154426