message: fix a missing thread join
diff: @@ -219,10 +219,8 @@ fn park_unpark() {
  // know Miri's timed synchronization primitives do not do that.
  assert!((200..1000).contains(&start.elapsed().as_millis()));
  -}
  -fn check_condvar() {
  - let _ = std::sync::Condvar::new();
  + t2.join().unwrap();
  }
  fn main() {
  @@ -236,5 +234,4 @@ fn main() {
  check_once();
  park_timeout();
  park_unpark();
  - check_condvar();
  }
  