* No need to check for both __gnu_linux__ and __linux__, latter is enough.
* Require libusb 1.0.13 to build - this makes LIBUSB_API_VERSION always defined.
* Include `<libusb.h>` not `<libusb-1.0/libusb.h>` - this will always work
if `pkg-config` is detected. For backwards compatibility still try building
without `pkg-config` present, but it is much less reliable and will not work on Mac.
* Bump copyright year.
* Clarify that uhubctl will automatically handle USB3 duality.
* Bump copyright year.
* Mention more Linux distributions where uhubctl was tested to work.
