[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/net/ipv6/route.c b/net/ipv6/route.c
index 269b760..6293cb9 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -556,8 +556,8 @@
 
 }
 
-struct rt6_info *rt6_lookup(struct net *net, struct in6_addr *daddr,
-			    struct in6_addr *saddr, int oif, int strict)
+struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
+			    const struct in6_addr *saddr, int oif, int strict)
 {
 	struct flowi fl = {
 		.oif = oif,
@@ -925,7 +925,7 @@
 
 struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
 				  struct neighbour *neigh,
-				  struct in6_addr *addr)
+				  const struct in6_addr *addr)
 {
 	struct rt6_info *rt;
 	struct inet6_dev *idev = in6_dev_get(dev);