[llvm] Correctly set pointer bit for aggregate values in SelectionDAGBuilder to fix CCIfPtr (PR #70554)

[Camil Staps via llvm-commits]

camilstaps wrote:

Also, in TargetLoweringBase I found one case where an ArgFlags struct is built for output arguments. Here `setPointer` is never used:

https://github.com/llvm/llvm-project/blob/497b2ebb9edcfd5315586b796f47589e9820b4b9/llvm/lib/CodeGen/TargetLoweringBase.cpp#L1711-L1758

I am not sure whether this is intentional, or an omission. I could add it if desired, but I was not sure when this function is used, exactly.

https://github.com/llvm/llvm-project/pull/70554