Replace mentions of struct libusb_context with the typedef libusb_context, as is expected by the API. Also fix init/exit to not handle the default context in any special way: the default context is reference counted, and it is thus NOT an error to call init on it multiple times, or exit for that matter afterwards.
Replace mentions of struct libusb_context with the typedef libusb_context, as is expected by the API.
Also fix init/exit to not handle the default context in any special way: the default context is reference counted, and it is thus NOT an error to call init on it multiple times, or exit for that matter afterwards.

usb4java/usb4java,zodsoft/usb4java