Fix race condition with C.libusb_handle_events that might still being called while libusb_exit is executed. Use C.libusb_handle_events_timeout_completed which accepts timeouts and pass 100 ms timeout. This is the recommended way to deal with this issue, see http://libusb.sourceforge.net/api-1.0/group__poll.html#ga43e52b912a760b41a0cf8a4a472fbd5b and http://libusb.sourceforge.net/api-1.0/group__poll.html#ga4989086e3f0327f3886a4c474ec7c327