[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/init/main.c b/init/main.c
index c9c311c..ff41006 100644
--- a/init/main.c
+++ b/init/main.c
@@ -47,6 +47,7 @@
 #include <linux/rmap.h>
 #include <linux/mempolicy.h>
 #include <linux/key.h>
+#include <net/sock.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -80,7 +81,6 @@
 static int init(void *);
 
 extern void init_IRQ(void);
-extern void sock_init(void);
 extern void fork_init(unsigned long);
 extern void mca_init(void);
 extern void sbus_init(void);