configure: error out when building X11 Vulkan without DRI3

Vulkan supports only DRI3 enabled X11 platforms. Make it obvious,
should one consider building without it.

Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
1 file changed