[llvm] [SPIRV] Add support for pointers to functions with aggregate args/returns as global variables / constant initialisers (PR #169595)

[Juan Manuel Martinez Caamaño via llvm-commits]

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

I'd like for somebody else to also take a look and validate before merging, to see if somebody has a better idea than the associate by name (as long as we get rid of it later it's ok for me).

https://github.com/llvm/llvm-project/pull/169595