dvdreadsrc: Work around GCC9 compiler warning
It's technically true but not for this specific type.
dvdreadsrc.c:394:65: error: taking address of packed member of ‘struct <anonymous>’ may result in an unaligned pointer value [-Werror=address-of-packed-member]
394 | gst_dvd_read_src_make_clut_change_event (src, src->cur_pgc->palette);
| ~~~~~~~~~~~~^~~~~~~~~
Edited by Sebastian Dröge