c++: Fix ICE in eval_annotations_of [PR123866]

c++: Fix ICE in eval_annotations_of [PR123866]

eval_annotations_of throws if the passed in reflection handle is not
eval_is_function (and various others).  Now, eval_is_function uses
maybe_get_first_fn to look through BASELINK/OVERLOAD etc., but
eval_annotations_of wasn't doing that and ICEd on
  else if (TYPE_P (r))
    r = TYPE_ATTRIBUTES (r);
  else if (DECL_P (r))
    r = DECL_ATTRIBUTES (r);
  else
    gcc_unreachable ();
because r isn't a decl nor type (nor REFLECT_BASE earlier).

2026-01-29  Jakub Jelinek  <jakub@redhat.com>

	PR c++/123866
	* reflect.cc (eval_annotations_of): Use maybe_get_first_fn.

	* g++.dg/reflect/annotations10.C: New test.