tproxy: added const specifiers to udp lookup functions

The parameters for various UDP lookup functions were non-const, even though
they could be const. TProxy has some const references and instead of
downcasting it, I added const specifiers along the path.
Signed-off-by: NBalazs Scheidler <bazsi@balabit.hu>
Signed-off-by: NKOVACS Krisztian <hidden@balabit.hu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>

net/ipv6/udp.c

@@ -122,8 +122,8 @@ static void udp_v6_rehash(struct sock *sk)
 
 static inline int compute_score(struct sock *sk, struct net *net,
 				unsigned short hnum,
-				struct in6_addr *saddr, __be16 sport,
-				struct in6_addr *daddr, __be16 dport,
+				const struct in6_addr *saddr, __be16 sport,
+				const struct in6_addr *daddr, __be16 dport,
 				int dif)
 {
 	int score = -1;
@@ -239,8 +239,8 @@ static struct sock *udp6_lib_lookup2(struct net *net,
 }
 
 static struct sock *__udp6_lib_lookup(struct net *net,
-				      struct in6_addr *saddr, __be16 sport,
-				      struct in6_addr *daddr, __be16 dport,
+				      const struct in6_addr *saddr, __be16 sport,
+				      const struct in6_addr *daddr, __be16 dport,
 				      int dif, struct udp_table *udptable)
 {
 	struct sock *sk, *result;