uloop: Fix incorrect timeout

uloop timeouts are calculated based on a time value that was fetched
before any callbacks were executed. Hence, the next timeout is off by
the time the callback execution took which can lead to strange side
effects.

Fix this by calculating the next timeout based on a fresh time value.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>

uloop.c

@@ -632,6 +632,7 @@ void uloop_run(void)
 
 		if (do_sigchld)
 			uloop_handle_processes();
+		uloop_gettime(&tv);
 		uloop_run_events(uloop_get_next_timeout(&tv));
 	}
 }