Fix use of inaccessible member in pr94052.C

The recent PR41437 fix exposed a latent use of an inaccessible member in
the below testcase.

	gcc/testsuite/ChangeLog:

	* g++.target/aarch64/pr94052.C: Give z::ad public access.

gcc/testsuite/g++.target/aarch64/pr94052.C

@@ -26,7 +26,7 @@ public:
   d x();
   d y();
 };
-class z : ad<int> {};
+class z : public ad<int> {};
 struct ae {
   p af;
 };