[llvm] [AMDGPU][GlobalISel] Combine (or s64, zext(s32)) (PR #151519)

[Mirko Brkušanin via llvm-commits]

mbrkusanin wrote:

I've moved the other combine to a separate PR (https://github.com/llvm/llvm-project/pull/151731)

This one now only covers or with zext. Helper C++ code is eliminated and it now it now covers both of:
(or i64:x, (zext i32:y))
(or (zext i32:y), i64:x)

https://github.com/llvm/llvm-project/pull/151519