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

[James Henderson via llvm-commits]

https://github.com/jh7370 approved this pull request.

LGTM, aside from a couple of remaining nits, but it would be worth getting a pair of eyes with real GOFF experience to sign off on it.

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