title: Issues with using ualarm
body: <p>In my code, i need to call sigalrm after 2 seconds. However, when i use             <code>ualarm(2000000, 0 )</code> it doesn't work. using <code>ualarm</code> less than 1 second works. Whereas <code>alarm(2)</code> works. Is there a reason why <code>ualarm</code> should be used at times over <code>alarm</code>? Is there any way to get <code>ualarm</code> to work for over 1 second?</p>