netfilter: ctnetlink: fix compilation with NF_CONNTRACK_EVENTS=n

This patch fixes compilation with NF_CONNTRACK_EVENTS=n and
NETFILTER_NETLINK_QUEUE_CT=y.

I'm leaving all those static inline functions that calculate the size
of the event message out of the ifdef area of NF_CONNTRACK_EVENTS since
they will not be included by gcc in case they are unused.
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_netlink.c

@@ -478,7 +478,6 @@ ctnetlink_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
 	return -1;
 }
 
-#ifdef CONFIG_NF_CONNTRACK_EVENTS
 static inline size_t
 ctnetlink_proto_size(const struct nf_conn *ct)
 {
@@ -565,6 +564,7 @@ ctnetlink_nlmsg_size(const struct nf_conn *ct)
 	       ;
 }
 
+#ifdef CONFIG_NF_CONNTRACK_EVENTS
 static int
 ctnetlink_conntrack_event(unsigned int events, struct nf_ct_event *item)
 {