`uloop_run_events` was not awakened when the first `timeout` was added.

[trnny]

libubox/uloop.c

Lines 667 to 678 in c1be505

	uloop_process_timeouts();
	if (do_sigchld)
	uloop_handle_processes();
	if (uloop_cancelled)
	break;
	next_time = uloop_get_next_timeout();
	if (timeout >= 0 && (next_time < 0 || timeout < next_time))
	next_time = timeout;
	uloop_run_events(next_time);

consider the following case:
uloop_run_events (-1) was entered when there is no next_timeout
and then executing uloop_timeout_add to add a timeout "task" that will not wake up uloop_run_events
the timeout "task" will never be executed.