rollup merge of #21389: retep998/timer

Fixes #20943 and adds a test for it
r? @alexcrichton

src/libstd/io/timer.rs

@@ -227,6 +227,12 @@ mod test {
     use thread::Thread;
     use time::Duration;
 
+    #[test]
+    fn test_timer_send() {
+        let mut timer = Timer::new().unwrap();
+        Thread::spawn(move || timer.sleep(Duration::milliseconds(1)));
+    }
+
     #[test]
     fn test_io_timer_sleep_simple() {
         let mut timer = Timer::new().unwrap();

src/libstd/sys/windows/timer.rs

@@ -48,9 +48,9 @@ pub enum Req {
     RemoveTimer(libc::HANDLE, Sender<()>),
 }
 
+unsafe impl Send for Timer {}
 unsafe impl Send for Req {}
 
-
 fn helper(input: libc::HANDLE, messages: Receiver<Req>, _: ()) {
     let mut objs = vec![input];
     let mut chans = vec![];