Expand test for full test coverage

Author: iluuu1994

ext/opcache/tests/gh21052.phpt

@@ -26,3 +26,7 @@ array(1) {
   [0]=>
   string(3) "foo"
 }
+array(1) {
+  [0]=>
+  string(3) "foo"
+}

ext/opcache/tests/gh21052_a.inc

@@ -7,3 +7,7 @@ class A {
         return ['foo'];
     }
 }
+
+function test() {
+    return ['foo'];
+}

ext/opcache/tests/gh21052_b.inc

@@ -2,3 +2,4 @@
 
 var_dump(A::C);
 var_dump(A::test());
+var_dump(test());