[NET]: Fix sparse warnings

Of this type, mostly:

CHECK   net/ipv6/netfilter.c
net/ipv6/netfilter.c:96:12: warning: symbol 'ipv6_netfilter_init' was not declared. Should it be static?
net/ipv6/netfilter.c:101:6: warning: symbol 'ipv6_netfilter_fini' was not declared. Should it be static?

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_tr.h b/include/linux/if_tr.h
index 3fba9e2..5502f59 100644
--- a/include/linux/if_tr.h
+++ b/include/linux/if_tr.h
@@ -43,12 +43,16 @@
 };
 
 #ifdef __KERNEL__
+#include <linux/config.h>
 #include <linux/skbuff.h>
 
 static inline struct trh_hdr *tr_hdr(const struct sk_buff *skb)
 {
 	return (struct trh_hdr *)skb->mac.raw;
 }
+#ifdef CONFIG_SYSCTL
+extern struct ctl_table tr_table[];
+#endif
 #endif
 
 /* This is an Token-Ring LLC structure */