c++: friend with redundant qualification [PR41723]

Different code paths were correctly choosing to look up D directly, since C
is the current instantiation, but here we decided to try to make it a
typename type, leading to confusion.  Fixed by using dependent_scope_p as we
do elsewhere.

gcc/cp/ChangeLog:

	PR c++/41723
	* parser.c (cp_parser_class_name): Check dependent_scope_p.

gcc/testsuite/ChangeLog:

	PR c++/41723
	* g++.dg/template/friend71.C: New test.

gcc/cp/parser.c

@@ -24639,7 +24639,7 @@ cp_parser_class_name (cp_parser *parser,
   const bool typename_p = (typename_keyword_p
 			   && parser->scope
 			   && TYPE_P (parser->scope)
-			   && dependent_type_p (parser->scope));
+			   && dependent_scope_p (parser->scope));
   /* Handle the common case (an identifier, but not a template-id)
      efficiently.  */
   if (token->type == CPP_NAME

gcc/testsuite/g++.dg/template/friend71.C

@@ -0,0 +1,8 @@
+// PR c++/41723
+
+template<class T>
+class C {
+  template <class U> class D {};
+
+  friend class C::D<int>;
+};