CARP_NL_VHID
snl_add_msg_attr_u32(&nw, CARP_NL_VHID, vhid);
snl_add_msg_attr_u32(&nw, CARP_NL_VHID, carpr->carpr_vhid);
{ .type = CARP_NL_VHID, .off = _OUT(carpr_vhid), .cb = snl_attr_get_uint32 },
{ .type = CARP_NL_VHID, .off = _OUT(vhid), .cb = nlattr_get_uint32 },
nlattr_add_u32(nw, CARP_NL_VHID, sc->sc_vhid);