ipv6: move csum_ipv6_magic() and udp6_csum_init() into static library

As suggested by David, udp6_csum_init() is too big to be inlined,
move it to ipv6 static library, net/ipv6/ip6_checksum.c.

And the generic csum_ipv6_magic() too.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip6_checksum.h b/include/net/ip6_checksum.h
index 652d3d3..7686e3f 100644
--- a/include/net/ip6_checksum.h
+++ b/include/net/ip6_checksum.h
@@ -35,63 +35,10 @@
 #include <linux/ipv6.h>
 
 #ifndef _HAVE_ARCH_IPV6_CSUM
-
-static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
-					  const struct in6_addr *daddr,
-					  __u32 len, unsigned short proto,
-					  __wsum csum)
-{
-
-	int carry;
-	__u32 ulen;
-	__u32 uproto;
-	__u32 sum = (__force u32)csum;
-
-	sum += (__force u32)saddr->s6_addr32[0];
-	carry = (sum < (__force u32)saddr->s6_addr32[0]);
-	sum += carry;
-
-	sum += (__force u32)saddr->s6_addr32[1];
-	carry = (sum < (__force u32)saddr->s6_addr32[1]);
-	sum += carry;
-
-	sum += (__force u32)saddr->s6_addr32[2];
-	carry = (sum < (__force u32)saddr->s6_addr32[2]);
-	sum += carry;
-
-	sum += (__force u32)saddr->s6_addr32[3];
-	carry = (sum < (__force u32)saddr->s6_addr32[3]);
-	sum += carry;
-
-	sum += (__force u32)daddr->s6_addr32[0];
-	carry = (sum < (__force u32)daddr->s6_addr32[0]);
-	sum += carry;
-
-	sum += (__force u32)daddr->s6_addr32[1];
-	carry = (sum < (__force u32)daddr->s6_addr32[1]);
-	sum += carry;
-
-	sum += (__force u32)daddr->s6_addr32[2];
-	carry = (sum < (__force u32)daddr->s6_addr32[2]);
-	sum += carry;
-
-	sum += (__force u32)daddr->s6_addr32[3];
-	carry = (sum < (__force u32)daddr->s6_addr32[3]);
-	sum += carry;
-
-	ulen = (__force u32)htonl((__u32) len);
-	sum += ulen;
-	carry = (sum < ulen);
-	sum += carry;
-
-	uproto = (__force u32)htonl(proto);
-	sum += uproto;
-	carry = (sum < uproto);
-	sum += carry;
-
-	return csum_fold((__force __wsum)sum);
-}
-
+__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
+			const struct in6_addr *daddr,
+			__u32 len, unsigned short proto,
+			__wsum csum);
 #endif
 
 static __inline__ __sum16 tcp_v6_check(int len,
@@ -126,4 +73,5 @@
 	__tcp_v6_send_check(skb, &np->saddr, &np->daddr);
 }
 
+int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh, int proto);
 #endif