message: abi: add `AddressSpace` field to `Primitive::Pointer`
  ...and remove it from `PointeeInfo`, which isn't meant for this.
  There are still various places (marked with FIXMEs) that assume all pointers
  have the same size and alignment. Fixing this requires parsing non-default
  address spaces in the data layout string, which will be done in a followup.
diff: @@ -35,7 +35,8 @@ pub(crate) fn scalar_to_clif_type(tcx: TyCtxt<'_>, scalar: Scalar) -> Type {
  },
  Primitive::F32 => types::F32,
  Primitive::F64 => types::F64,
  - Primitive::Pointer => pointer_ty(tcx),
  + // FIXME(erikdesjardins): handle non-default addrspace ptr sizes
  + Primitive::Pointer(_) => pointer_ty(tcx),
  }
  }
  