Windows save in hardware_keycode an information which is not so low
level and some application require the hardware scancode.
As Windows provides this information save it in GdkEventPrivate
and provide a function to get this information.
For no Windows system the function return the hardware_keycode instead.
Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
https://bugzilla.gnome.org/show_bug.cgi?id=765259