[llvm] [GOFF] Add writing of section symbols (PR #133799)

[Fangrui Song via llvm-commits]

MaskRay wrote:

I want to land https://github.com/MaskRay/llvm-project/pull/4 to fix mcfragment usage within MCContext and fix an ELF/COFF section symbol bug, and am running into failing zos-section-1.ll and zos-section-2.ll tests.

The absence of accompanying test/MC tests and the use of hex bytes in the test/CodeGen tests make debugging challenging for generic interface improvement.. I looked at a few pages on the opaque https://www.ibm.com/docs/en/zos/2.4.0?topic=goff-record-formats and still did not get the idea. I suspect GOFF’s intricacies could pose ongoing challenges for improving generic code (MC layer, binary utilities)...

https://github.com/llvm/llvm-project/pull/133799