[llvm] [MemProf][PGO] Prevent dropping of profile metadata during optimization (PR #121359)

[Snehasish Kumar via llvm-commits]

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

lgtm for memprof. Maybe consider filing an issue and add a FIXME for the agreed up on changes? 

https://github.com/llvm/llvm-project/pull/121359