[llvm] [SystemZ][z/OS] yaml2obj for header and end records (PR #73859)

[James Henderson via llvm-commits]

https://github.com/jh7370 requested changes to this pull request.

@ysyeda, please don't resolve conversations that I've initiated, as I use the "resolved" state to determine whether or not I have reviewed the change and am happy with it. For more context, see https://discourse.llvm.org/t/rfc-github-pr-resolve-conversation-button/73178.

For ELF and COFF at least, most of the tests are contained in test/tools/yaml2obj. It might make sense to move the tests there.

https://github.com/llvm/llvm-project/pull/73859