[IPV6]: Support IPV6_{RECV,}TCLASS socket options / ancillary data.

Based on patch from David L Stevens <dlstevens@us.ibm.com>

Signed-off-by: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/include/net/transp_v6.h b/include/net/transp_v6.h
index 8b075ab..4e86f2d 100644
--- a/include/net/transp_v6.h
+++ b/include/net/transp_v6.h
@@ -37,7 +37,7 @@
 extern int			datagram_send_ctl(struct msghdr *msg,
 						  struct flowi *fl,
 						  struct ipv6_txoptions *opt,
-						  int *hlimit);
+						  int *hlimit, int *tclass);
 
 #define		LOOPBACK4_IPV6		__constant_htonl(0x7f000006)