[llvm] [GlobalIsel] Combine G_UNMERGE_VALUES from opaque vectors into scalars (PR #113040)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

I am open to suggestions, but `G_OPAQUE` is like not important. You don't need to know what defined the register.

https://github.com/llvm/llvm-project/pull/113040