[llvm] [CSSPGO] Fix the issue of missing callee profile matches (PR #85715)

[Lei Wang via llvm-commits]

wlei-llvm wrote:

> I meant the problem that applying stale profile matching to a perfectly matched profile is not a no-op. And we should improve the algorithm to try to make it a no-op, hoping that it will help improve things overall even for mismatched cases..

I see, makes sense to me, will try to improve this. 

https://github.com/llvm/llvm-project/pull/85715