[lld] [lld-macho] Implement ObjC category merging (-objc_category_merging) (PR #82928)

[via llvm-commits]

alx32 wrote:

> Do you expected such a many corrupted data in the catlist section?

No this shouldn't really happen unless there are changes made in the clang front-end and there is a mismatch. But most likely there will be edge cases happening that are not obvious now. That's why I think the errors are useful in prod vs asserts. I do not know of (valid) test cases to surface the errors, other than maybe introducing invalid data. 

https://github.com/llvm/llvm-project/pull/82928