[llvm] [ctxprof] Profile section for flat profiles (PR #129932)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

### Merge activity

* **Mar 7, 12:17 AM EST**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/129932).


https://github.com/llvm/llvm-project/pull/129932