Disable broken 'this' check in director_unroll_runme.php

This was comparing an unset property on two objects matched - they
do, but the check we actually intend here is that they wrap the same C++
object.  We don't seem to be able to accomplish the desired check for
PHP, so just disable this for now.

Examples/test-suite/php/director_unroll_runme.php

@@ -23,7 +23,10 @@ $b = new Bar();
 $b->set($a);
 $c = $b->get();
 
-check::equal($a->this, $c->this, "this failed");
+// FIXME: This doesn't work for checking that they wrap the same C++ object
+// because the two objects have different PHP resources, and we can't easily
+// look inside those resources to see which C++ objects they refer to.
+//check::equal($a->_cPtr, $c->_cPtr, "_cPtr check failed");
 
 check::done();
 ?>