[llvm] [yaml2obj][XOFF] Update yaml2obj for XCOFF to create valid XCOFF files in more cases. (PR #77620)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

I don't think all the error cases have tests? Also you need to ensure that all your optional fields are tested (showing default behaviour when not specified).

https://github.com/llvm/llvm-project/pull/77620