igmp: Avoid zero delay when receiving odd mixture of IGMP queries

Commit 5b7c84066733c5dfb0e4016d939757b38de189e4 ('ipv4: correct IGMP
behavior on v3 query during v2-compatibility mode') added yet another
case for query parsing, which can result in max_delay = 0.  Substitute
a value of 1, as in the usual v3 case.

Reported-by: Simon McVittie <smcv@debian.org>
References: http://bugs.debian.org/654876
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
static struct sk_buff *add_grhead(struct sk_buff *skb, struct ip_mc_list *pmc,
	int type, struct igmpv3_grec **ppgr)
{
	struct net_device *dev = pmc->interface->dev;
	struct igmpv3_report *pih;
	struct igmpv3_grec *pgr;

	if (!skb)
		skb = igmpv3_newpack(dev, dev->mtu);
	if (!skb)
		return NULL;
	pgr = (struct igmpv3_grec *)skb_put(skb, sizeof(struct igmpv3_grec));
	pgr->grec_type = type;
	pgr->grec_auxwords = 0;
	pgr->grec_nsrcs = 0;
	pgr->grec_mca = pmc->multiaddr;
	pih = igmpv3_report_hdr(skb);
	pih->ngrec = htons(ntohs(pih->ngrec)+1);
	*ppgr = pgr;
	return skb;
}

static struct sk_buff *add_grhead(struct sk_buff *skb, struct ip_mc_list *pmc,
	int type, struct igmpv3_grec **ppgr)
{
	struct net_device *dev = pmc->interface->dev;
	struct igmpv3_report *pih;
	struct igmpv3_grec *pgr;

	if (!skb)
		skb = igmpv3_newpack(dev, dev->mtu);
	if (!skb)
		return NULL;
	pgr = (struct igmpv3_grec *)skb_put(skb, sizeof(struct igmpv3_grec));
	pgr->grec_type = type;
	pgr->grec_auxwords = 0;
	pgr->grec_nsrcs = 0;
	pgr->grec_mca = pmc->multiaddr;
	pih = igmpv3_report_hdr(skb);
	pih->ngrec = htons(ntohs(pih->ngrec)+1);
	*ppgr = pgr;
	return skb;
}
