Pickle test additions

These are not working yet for all combinations of builtin and PY3
The goal is to have a sensible default error that states that
pickling is not supported.

Examples/test-suite/python_pickle.i

@@ -48,4 +48,9 @@ struct PickleMe {
       std::cout << "In C++ constructor " << " [" << msg << "]" << std::endl;
   }
 };
+
+struct NotForPickling {
+  std::string msg;
+  NotForPickling(const std::string& msg) : msg(msg) {}
+};
 %}