[php] Fix -prefix when there are subclasses

The calls to the parent class' magic __get, __set and __isset methods
weren't getting the prefix.

Examples/test-suite/php/prefix_runme.php

@@ -5,7 +5,7 @@ require "tests.php";
 // No new functions
 check::functions(array());
 // New classes
-check::classes(array('ProjectFoo'));
+check::classes(array('ProjectBar','ProjectFoo'));
 // No new vars
 check::globals(array());
 

Examples/test-suite/prefix.i

@@ -11,4 +11,10 @@ public:
   }
 };
 
+// This failed in git pre 4.1.0 - the calls to the parent class' magic __get,
+// __set and __isset methods weren't getting the prefix.
+class Bar : public Foo {
+public:
+};
+
 %}