bgpd: don't use BGP_ATTR_VNC(255) unless ENABLE_BGP_VNC_ATTR is defined

Signed-off-by: Lou Berger <lberger@labn.net>
static struct transit *transit_intern(struct transit *transit)
{
	struct transit *find;

	find = hash_get(transit_hash, transit, transit_hash_alloc);
	if (find != transit)
		transit_free(transit);
	find->refcnt++;

	return find;
}

static struct transit *transit_intern(struct transit *transit)
{
	struct transit *find;

	find = hash_get(transit_hash, transit, transit_hash_alloc);
	if (find != transit)
		transit_free(transit);
	find->refcnt++;

	return find;
}
