[clang] [llvm] [MC,llvm-readobj,yaml2obj] Support CREL relocation format (PR #91280)

[Fangrui Song via cfe-commits]

MaskRay wrote:

> Just noting that I've taken another look through the whole thing and I have no new comments.

Thanks for the review! @dwblaikie @jh7370 @smithp35 If the current version looks good to you, may I get explicit approval?

https://github.com/llvm/llvm-project/pull/91280