devel/android-tools-fastboot: unbreak against libusb-1.0.9 from sf.net

inb4 someone actually tests on NetBSD or OpenBSD...

files/usb_freebsd.c:57:2: error: must

use 'struct' tag to refer to type 'libusb_device_descriptor'
  libusb_device_descriptor ddesc;
  ^
  struct

files/usb_freebsd.c:58:2: error: must

use 'struct' tag to refer to type 'libusb_config_descriptor'
  libusb_config_descriptor *pcfg;
  ^
  struct

2 errors generated.

Tested by: md5