Since FreeBSD has new USB stack, freeglut normally doesn't build on FreeBSD 8
(yet). To workaround this a small patch adds one include file and comments out
content of one function (only leaves return NULL).

This might cause side effects.  Joysticks do not work, and there might be ports
that do not compile or applications that crash because of this.

Do not hesitate to contact x11@FreeBSD.org if there are any issues and side
effects because of this.