[IPV6]: Added GSO support for TCPv6

This patch adds GSO support for IPv6 and TCPv6.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0bb0ac9..b7cf26e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2215,6 +2215,7 @@
 out:
 	return segs;
 }
+EXPORT_SYMBOL(tcp_tso_segment);
 
 extern void __skb_cb_too_small_for_tcp(int, int);
 extern struct tcp_congestion_ops tcp_reno;