message: Fix memory leak in last function
diff: @@ -69,6 +69,9 @@ template <bool LAST, bool SKIP_NULLS>
  struct FirstFunctionString : public FirstFunctionBase {
  template <class STATE>
  static void SetValue(STATE *state, string_t value, bool is_null) {
  + if (LAST && state->is_set) {
  + Destroy(state);
  + }
  if (is_null) {
  if (!SKIP_NULLS) {
  state->is_set = true;
  