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

[Alex Voicu via llvm-commits]

AlexVlx wrote:

I will merge this so as to unblock workflows that are running into the issue and I can start making some progress on subsequent patches; if there are late coming objections or observations we can always iterate.

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