The gen-header.sh and gen-shader-headers.sh scripts are missing an SPDX header. Fix it. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com> Reviewed-by: Bryan O'Donoghue <bod.linux@nxsw.ie>