Add new API function libusb_get_device_speed()
Reworked version of my earlier patch, largely modelled after (if not
copy and pasted from) Trygve Laugstøl's <trygvis@inamo.no> similar
commit
5a6541e0d80fb1f21e2b960bc2337a612f9d74fb in
git://git.libusb.org/libusb-trygvis.git
http://git.libusb.org/libusb-trygvis.git
http://git.libusb.org/?p=libusb-trygvis.git;a=commitdiff;h=
5a6541e0d
This patch does not add any OS specific code. The supporting code in
each backend follows in separate patches. References #45.
Signed-off-By: Hans de Goede <hdegoede@redhat.com>