c++/reflection: tweak for eval_has_template_arguments

c++/reflection: tweak for eval_has_template_arguments

As discussed in
<https://gcc.gnu.org/pipermail/gcc-patches/2026-January/705756.html>:

> For reflection it's probably best to go with
>
> if (TYPE_P (r) && typedef_variant_p (r))
>   return alias_template_specialization_p (r, nt_opaque);
>
> and not get into primary_template_specialization_p at all.

Here in a patch form.

gcc/cp/ChangeLog:

	* reflect.cc (eval_has_template_arguments): Return immediately after
	checking alias_template_specialization_p.

Reviewed-by: Jason Merrill <jason@redhat.com>