netfilter: conntrack: Make nf_ct_protos store const l4proto pointers

Needed for newer clang versions.

Change-Id: I7e9de21eb8de5e56404dec43f5e5de31148c9eb0

net/netfilter/nf_conntrack_proto.c

@@ -43,7 +43,7 @@
 
 extern unsigned int nf_conntrack_net_id;
 
-static struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
+static const struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
 
 static DEFINE_MUTEX(nf_ct_proto_mutex);
 
@@ -229,12 +229,12 @@ int nf_ct_l4proto_register_one(const struct nf_conntrack_l4proto *l4proto)
 	mutex_lock(&nf_ct_proto_mutex);
 	if (!nf_ct_protos[l4proto->l3proto]) {
 		/* l3proto may be loaded latter. */
-		struct nf_conntrack_l4proto __rcu **proto_array;
+		struct nf_conntrack_l4proto __rcu const **proto_array;
 		int i;
 
 		proto_array =
 			kmalloc_array(MAX_NF_CT_PROTO,
-				      sizeof(struct nf_conntrack_l4proto *),
+				      sizeof(const struct nf_conntrack_l4proto *),
 				      GFP_KERNEL);
 		if (proto_array == NULL) {
 			ret = -ENOMEM;