Log Message:
Update devel/libusb-compat to version 0.1.6-rc2 (as 0.1.6rc2 here)

From the ChangeLog:

    tag the 0.1.6-rc1 release
    Add -no-undefined to LDFLAGS
    Add some missing definitions
    Use C99 standard fixed width integer types in usb.h
    Prevent libusb-1.0 library symbol clash
    Add a library destructor to handle cleaning up libusb.
    Revert "Link with -znodelete to disallow unloading"
    Revert "use atexit() to call libusb_exit()"
    Link with -znodelete to disallow unloading

Also changes the master site to GitHub.

Tested on NetBSD/amd64.

TODO: offer as an alternative to devel/libusb.