message: Allow cranelift to handle atomic pointers
diff: macro validate_atomic_type($fx:ident, $intrinsic:ident, $span:ident, $ty:expr) {
  match $ty.kind() {
  - ty::Uint(_) | ty::Int(_) => {}
  + ty::Uint(_) | ty::Int(_) | ty::RawPtr(..) => {}
  _ => {
  $fx.tcx.sess.span_err(
  $span,
  &format!(
  - "`{}` intrinsic: expected basic integer type, found `{:?}`",
  + "`{}` intrinsic: expected basic integer or raw pointer type, found `{:?}`",
  $intrinsic, $ty
  ),
  );
  