[llvm] [IPO] NFC: avoid recalculating FunctionId hashes during ProfiledCallGraph construction (PR #109014)

[via llvm-commits]

itrofimow wrote:

Hi @nikic! I see you are the one who recently reviewed a PR touching `ProfiledCallGraph.h`with the similar speedup idea, would you be able to give this PR a look?

https://github.com/llvm/llvm-project/pull/109014