Fixed unused argument warning

SimoxUtility/xml/rapidxml/rapidxml_print.hpp

@@ -248,6 +248,8 @@ namespace rapidxml
         template<class OutIt, class Ch>
         inline OutIt print_attributes(OutIt out, const xml_node<Ch>* node, int flags)
         {
+            (void) flags;  // Unused.
+
             for (xml_attribute<Ch>* attribute = node->first_attribute(); attribute; attribute = attribute->next_attribute())
             {
                 if (attribute->name() && attribute->value())