VIFF_IGMPV1
| IGMPV1 { v->uv_flags |= VIFF_IGMPV1; }
if (v->uv_flags & VIFF_IGMPV1) fprintf(fp, " IGMPv1");
(v->uv_flags & VIFF_IGMPV1) ? 0 :
(v->uv_flags & VIFF_IGMPV1) ? 0 :
if (!(v->uv_flags & VIFF_QUERIER) || (v->uv_flags & VIFF_IGMPV1))