pidgin/pidgin

Fix signed/unsigned comparison warning.
release-2.x.y
2014-11-12, Elliott Sales de Andrade
a3fe30a2666b
Fix signed/unsigned comparison warning.

The test still works correctly without the fix, but this is quieter.
For information on hacking on Pidgin, Finch, or libpurple, see:
http://developer.pidgin.im