Handle the unported case by issuing a build-time and run-time warning.
And add support for FreeBSD kernel based systems, by using the
VT_GETINDEX ioctl to check if the file descriptor is on a virtual
console.
Signed-off-by: Guillem Jover <guillem@hadrons.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>