[llvm] [LIR][profcheck] Reuse the loop's exit condition profile (PR #164523)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

@jdenny-ornl I'll merge this, and can follow up with the `llvm.loop.estimated_trip_count` propagation if that is the right thing to do (somewhat arguably separate change anyway)

https://github.com/llvm/llvm-project/pull/164523