modules_k/rls: Fixed memory leak in process_list_and_exec()

- xmlFree was called on rl_doc, but xmlFreeDoc should have been called
- Found and fixed by Paul Pankhurst @ Crocodile RCS
(cherry picked from commit ca938a37c87782c709b441c682f723d07b05c64c)

modules_k/rls/notify.c

@@ -979,7 +979,7 @@ int process_list_and_exec(xmlNodePtr list_node, str username, str domain,
 						LM_DBG("calling myself for rl_node\n");
 						res = process_list_and_exec(rl_node, username, domain, function, param);
 						xmlFree(uri);
-						xmlFree(rl_doc);
+						xmlFreeDoc(rl_doc);
 					}
 					else
 					{