message: simplify async-fn tests
diff: @@ -40,6 +40,7 @@ async fn includes_never(crash: bool, x: u32) -> u32 {
  result
  }
  +fn run_fut(mut fut: impl Future<Output=u32>, output: u32) {
  fn raw_waker_clone(_this: *const ()) -> RawWaker {
  panic!("unimplemented");
  }
  @@ -58,20 +59,16 @@ static RAW_WAKER: RawWakerVTable = RawWakerVTable::new(
  raw_waker_drop,
  );
  -fn main() {
  - let x = 5;
  - let mut fut = foo(&x, 7);
  let waker = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &RAW_WAKER)) };
  let mut context = Context::from_waker(&waker);
  - assert_eq!(unsafe { Pin::new_unchecked(&mut fut) }.poll(&mut context), Poll::Ready(31));
  + assert_eq!(unsafe { Pin::new_unchecked(&mut fut) }.poll(&mut context), Poll::Ready(output));
  +}
  - let mut fut = build_aggregate(1, 2, 3, 4);
  - let waker = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &RAW_WAKER)) };
  - let mut context = Context::from_waker(&waker);
  - assert_eq!(unsafe { Pin::new_unchecked(&mut fut) }.poll(&mut context), Poll::Ready(10));
  +fn main() {
  + let x = 5;
  + run_fut(foo(&x, 7), 31);
  - let mut fut = includes_never(false, 4);
  - let waker = unsafe { Waker::from_raw(RawWaker::new(ptr::null(), &RAW_WAKER)) };
  - let mut context = Context::from_waker(&waker);
  - assert_eq!(unsafe { Pin::new_unchecked(&mut fut) }.poll(&mut context), Poll::Ready(16));
  + run_fut(build_aggregate(1, 2, 3, 4), 10);
  +
  + run_fut(includes_never(false, 4), 16);
  }
  