const runtime.mutex_sleeping

5 uses

	runtime (current package)
		lock_futex.go#L28: 	mutex_sleeping = 2
		lock_futex.go#L101: 		v = atomic.Xchg(key32(&l.key), mutex_sleeping)
		lock_futex.go#L105: 		wait = mutex_sleeping
		lock_futex.go#L106: 		futexsleep(key32(&l.key), mutex_sleeping, -1)
		lock_futex.go#L119: 	if v == mutex_sleeping {