message: Fix shutdown issue in calculator example
diff: @@ -30,7 +30,7 @@ class typed_calculator;
  // function-based, dynamically typed, event-based API
  behavior calculator_fun(event_based_actor*) {
  - return behavior{
  + return {
  [](add_atom, int a, int b) {
  return a + b;
  },
  @@ -144,6 +144,8 @@ void caf_main(actor_system& system) {
  auto a6 = system.spawn<typed_calculator>();
  scoped_actor self{system};
  tester(self, a1, 1, 2, a2, 3, 4, a3, 5, 6, a4, 7, 8, a5, 9, 10, a6, 11, 12);
  + self->send_exit(a1, exit_reason::user_shutdown);
  + self->send_exit(a4, exit_reason::user_shutdown);
  }
  } // namespace <anonymous>
  