To support libusb_set_option and usbdk backend

[Xiaofan Chen]

Ref:
https://github.com/pyusb/pyusb/issues/200
https://github.com/libusb/libusb/issues/443
https://github.com/libusb/libusb/wiki/Windows#Driver_Installation

This will help to support the possibility of using usbdk
backend under Windows.

usbdk backend has an advantage that you can keep the
vendor FTDI driver (for VCP and D2XX function) and
at the same time you can use libftdi/libusb/etc.