[llvm] [PGO]add bitcode-use-sample-profile (PR #66178)

[Teresa Johnson via llvm-commits]

https://github.com/teresajohnson requested changes to this pull request.

I don't really follow the description of this from the conversation (I think the commit itself also needs a description which seems to be missing here). The change also needs a test case, which would help clarify what problem this is trying to solve.

I've added another reviewer who is more familiar with the sample profiler than I
(@huangjd). 

https://github.com/llvm/llvm-project/pull/66178