small dtrace patch for mtr

[Kristofer Pettersson]

https://intranet.mysql.com/secure/paste/displaypaste.php?codeid=7858

For some strange reason I can 't commit when I use X-forwardning on a 
macosx. It is probably an easy fix but who gives a damn. :)

Please give a review on the above patch. My knowledge of perl is limited 
so the patch might not be optimal.

Cheers,
Kristofer