[X86] When manually creating intrinsic nodes in X86ISelLowering, make sure we...

[X86] When manually creating intrinsic nodes in X86ISelLowering, make sure we use getTargetConstant and pointer type for the intrinsic ID.

Doesn't really matter in practice but that's how the nodes are
normally created by SelectionDAGBuilder. So we should match.

Found by temporarily hacking type checks into isel table.