netfilter: cleanup netfilter_ipv6.h userspace header

Kernel functions are not for userspace.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter_ipv6.h

@@ -70,6 +70,8 @@ enum nf_ip6_hook_priorities {
 	NF_IP6_PRI_LAST = INT_MAX,
 };
 
+#ifdef  __KERNEL__
+
 #ifdef CONFIG_NETFILTER
 extern int ip6_route_me_harder(struct sk_buff *skb);
 extern __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
@@ -82,4 +84,6 @@ static inline int ipv6_netfilter_init(void) { return 0; }
 static inline void ipv6_netfilter_fini(void) { return; }
 #endif /* CONFIG_NETFILTER */
 
+#endif /* __KERNEL__ */
+
 #endif /*__LINUX_IP6_NETFILTER_H*/