This way if the user enables the documentation and the dependencies are missing the configure fails. Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Ricardo Ribalda <ricardo@ribalda.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>