[llvm] [SPIR-V] Add NonSemantic.AuxData emission (-spirv-preserve-auxdata) and preserve available_externally linkage (PR #200002)

[Dmitry Sidorov via llvm-commits]

https://github.com/MrSidims commented:

Much better, thanks!

Please remove available_externally  from the PR name. Keep it in the description.

Does the patch handle a case for value/numeric metadata aka (!{i32 5})?

https://github.com/llvm/llvm-project/pull/200002