[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/net/addrconf.h b/include/net/addrconf.h
index a0ed936..750e250 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -45,6 +45,7 @@
 
 #ifdef __KERNEL__
 
+#include <linux/config.h>
 #include <linux/netdevice.h>
 #include <net/if_inet6.h>
 #include <net/ipv6.h>
@@ -238,5 +239,10 @@
 		addr->s6_addr32[3] == htonl(0x00000002));
 }
 
+#ifdef CONFIG_PROC_FS
+extern int if6_proc_init(void);
+extern void if6_proc_exit(void);
+#endif
+
 #endif
 #endif