runtime: fix coroutine handle race during sleep

Author: mertcandav

std/runtime/proc.jule

@@ -1217,8 +1217,9 @@ async fn sleep(dur: sleepDuration) {
 	mut c := m.c
 	when := nanotime() + dur
 	mut t := timer.new(when, nil, uintptr(&c), 0)
+	m.pp.timers.mu.lock()
 	m.pp.timers.push(t)
-	park(&c, 0, reasonSleep).await
+	park(&c, uintptr(&m.pp.timers.mu), reasonSleep).await
 }
 
 // Destroys all retired coroutine frames for the current worker thread.

std/runtime/timer.jule

@@ -94,14 +94,13 @@ impl timerheap {
 	}
 
 	// Inserts a timer into the heap.
+	// Timer lock must be held.
 	#disable nilptr
 	fn push(mut *self, mut t: &timer) {
-		t.mu.lock()
 		t.theap = unsafe { (&timerheap)(self) }
 		t.index = len(self.data)
 		self.data = append(self.data, t)
 		self.siftup(t.index)
-		t.mu.unlock()
 	}
 
 	// Removes and returns the earliest timer.