Port src/utils/sixpair.c to libusb-1.0

[davide125]

src/utils/sixpair.c is the only component of this codebase that is still using the deprecated libusb 0.1 API. Porting it to libusb-1.0 would allow dropping this dependency, and in turn make psmoveapi easier to package (as the 0.1 compat layer is also considered deprecated and in the process of being removed from distributions).

[thp]

Sounds good, patches gladly accepted.