[IPV6]: Make address arguments const.

- net/ipv6/addrconf.c:
	ipv6_get_ifaddr(), ipv6_dev_get_saddr()
- net/ipv6/mcast.c:
	ipv6_sock_mc_join(), ipv6_sock_mc_drop(),
	inet6_mc_check(),
	ipv6_dev_mc_inc(), __ipv6_dev_mc_dec(), ipv6_dev_mc_dec(),
	ipv6_chk_mcast_addr()
- net/ipv6/route.c:
	rt6_lookup(), icmp6_dst_alloc()
- net/ipv6/ip6_output.c:
	ip6_nd_hdr()
- net/ipv6/ndisc.c:
	ndisc_send_ns(), ndisc_send_rs(), ndisc_send_redirect(),
	ndisc_get_neigh(), __ndisc_send()

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index 1642423..9c451ff 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -94,17 +94,17 @@
 
 extern void			ndisc_send_ns(struct net_device *dev,
 					      struct neighbour *neigh,
-					      struct in6_addr *solicit,
-					      struct in6_addr *daddr,
-					      struct in6_addr *saddr);
+					      const struct in6_addr *solicit,
+					      const struct in6_addr *daddr,
+					      const struct in6_addr *saddr);
 
 extern void			ndisc_send_rs(struct net_device *dev,
-					      struct in6_addr *saddr,
-					      struct in6_addr *daddr);
+					      const struct in6_addr *saddr,
+					      const struct in6_addr *daddr);
 
 extern void			ndisc_send_redirect(struct sk_buff *skb,
 						    struct neighbour *neigh,
-						    struct in6_addr *target);
+						    const struct in6_addr *target);
 
 extern int			ndisc_mc_map(struct in6_addr *addr, char *buf, struct net_device *dev, int dir);
 
@@ -134,7 +134,7 @@
 extern void 			inet6_ifinfo_notify(int event,
 						    struct inet6_dev *idev);
 
-static inline struct neighbour * ndisc_get_neigh(struct net_device *dev, struct in6_addr *addr)
+static inline struct neighbour * ndisc_get_neigh(struct net_device *dev, const struct in6_addr *addr)
 {
 
 	if (dev)