Older versions of libusb return 0 on success for
usb_find_busses(); however, since the check on
usb_find_busses was checking for <= 0, this causes it
to fail (I did this on a RedHat 9 box with libusb
0.1.6). This patch just makes it so that the check is
for < 0, which would indicate an error. Correspondence
can be sent to firstname.lastname@example.org. Thank you.