[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/socket.h b/include/linux/socket.h
index acc55aa..1739c2d 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -26,6 +26,13 @@
 #include <linux/types.h>		/* pid_t			*/
 #include <linux/compiler.h>		/* __user			*/
 
+extern int sysctl_somaxconn;
+extern void sock_init(void);
+#ifdef CONFIG_PROC_FS
+struct seq_file;
+extern void socket_seq_show(struct seq_file *seq);
+#endif
+
 typedef unsigned short	sa_family_t;
 
 /*