[llvm] [GlobalISel] Constant-fold G_PTR_ADD with different type sizes (PR #81473)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

Is constant-folding G_PTR_ADD target-independent? Does it depend on the address space? Do AMDGPU and AArch64 do the same for *all* address spaces?

https://github.com/llvm/llvm-project/pull/81473