[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/kernel/sysctl.c b/kernel/sysctl.c
index 3e0bbee..8e56e24 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -31,6 +31,7 @@
 #include <linux/smp_lock.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/net.h>
 #include <linux/sysrq.h>
 #include <linux/highuid.h>
 #include <linux/writeback.h>
@@ -136,9 +137,6 @@
 
 static ctl_table kern_table[];
 static ctl_table vm_table[];
-#ifdef CONFIG_NET
-extern ctl_table net_table[];
-#endif
 static ctl_table proc_table[];
 static ctl_table fs_table[];
 static ctl_table debug_table[];