Log Message:
Import global switch for libusb's implementation [2/2]

This switch is meant to be used by packages requiring an implementation of the
former libusb (as in devel/libusb). The original implementation can be
chosen by setting LIBUSB_TYPE to "native".

The alternative implementation libusb-compat (as in devel/libusb-compat) wraps
libusb1 (in devel/libusb1). This implementation can be chosen by setting
LIBUSB_TYPE to "compat". On NetBSD, it has the advantage of not \ 
requiring root
privileges to locate and use USB devices without a kernel driver.

This second part switches packages using libusb to this framework. It does not
change compilation options or dependencies at this point.

Compile-tested on most packages affected and available on NetBSD/amd64.