inet: constify ip headers and in6_addr

Add const qualifiers to structs iphdr, ipv6hdr and in6_addr pointers
where possible, to make code intention more obvious.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 98348d5..aca8ef4 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -198,12 +198,12 @@
 						  pol_lookup_t lookup);
 
 extern struct fib6_node		*fib6_lookup(struct fib6_node *root,
-					     struct in6_addr *daddr,
-					     struct in6_addr *saddr);
+					     const struct in6_addr *daddr,
+					     const struct in6_addr *saddr);
 
 struct fib6_node		*fib6_locate(struct fib6_node *root,
-					     struct in6_addr *daddr, int dst_len,
-					     struct in6_addr *saddr, int src_len);
+					     const struct in6_addr *daddr, int dst_len,
+					     const struct in6_addr *saddr, int src_len);
 
 extern void			fib6_clean_all(struct net *net,
 					       int (*func)(struct rt6_info *, void *arg),