[llvm] MCExpr-ify SIProgramInfo (PR #88257)

[Janek van Oirschot via llvm-commits]

JanekvO wrote:

> A layering question: The new test heavily reaches into llvm/lib/Target/AMDGPU internals. Given that, why is it in unittests/MC/AMDGPU instead of unittests/Target/AMDGPU

What I was (hoping) to test is scoped to the MC layer part. Despite having written it, this test didn't sit too well with me. I was thinking to remove/change it as soon as I have the patch in that will allow unresolved MCExprs for the SIProgramInfo members to be parsed from asm so I'm not against removing the unittest altogether if that's in favor.

https://github.com/llvm/llvm-project/pull/88257