[clang] [Clang] Make enums trivially equality comparable (PR #133587)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

The summary should not merely link to an issue but describe the problem as well. Two reasons:

1) for folks reading this in git log
2) The issue may not totally explain what is going on.

I actually did not get it at first b/c the issue talks about *char* and *std::byte* it took me a bit to realize oh yes *std::byte* is an enum. A good summary would have clarified this for reviewers.

https://github.com/llvm/llvm-project/pull/133587