OpenBSD: Provide libusb_get_device_speed() data
OpenBSD: Provide libusb_get_device_speed() data

Because the different speed values used by the libusb and OpenBSD's
usb_device_info structure are compatible, keep the code simple and
just copy the value returned by the USB_GET_DEVICEINFO ioctl() call.

Fixes #45.

SpecLad/libusb-android,bert/libusb,dasdeepak/libusb,tenderlove/libusb,ashima/libusb,mojca/libusb_pico,Distrotech/libusb,ashima/libusb,dasdeepak/libusb,SpecLad/libusb-android,legege/libusb,bert/libusb,legege/libusb,ashima/libusb,mojca/libusb_pico,hjelmn/libusb-darwin,legege/libusb,tenderlove/libusb,Distrotech/libusb,dasdeepak/libusb,SpecLad/libusb-android,Distrotech/libusb,hjelmn/libusb-darwin