[clang] [clang] WIP: Warn on mismatched RequiresCapability attributes (PR #67520)

[Aaron Puchert via cfe-commits]

aaronpuchert wrote:

That might not be enough. A function might not be used (or even referenced) in the TU that defines it, but only in other TUs. But it would certainly catch a number of issues already.

https://github.com/llvm/llvm-project/pull/67520