[clang] [C23] Handle type compatibility for enumerations better (PR #150282)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

There's no release note because this is covered by the existing one about N3037. Assuming this patch is landed in time, it would be cherry-picked to the 21.x branch (which also has the release note). If it's not cherry-picked, then I'll add a release note to the main branch.

https://github.com/llvm/llvm-project/pull/150282