[llvm] [BOLT] Introduce profile-use-std-hash (PR #74253)

[Maksim Panchenko via llvm-commits]

https://github.com/maksfb commented:

How about we write a new field to YAML with a hash function name/ID? In the reader, we default to `std::hash` for backwards compatibility as you already do. If we are not planning on using `std::hash` in the future (for writing), perhaps the option is not needed at all? We can likely have a couple of binary/YAML test cases that verify backwards compatibility.

Suggestion for the title: "Provide backwards compatibility for YAML profile with std::hash".

https://github.com/llvm/llvm-project/pull/74253