[X.25]: Adds /proc/sys/net/x25/x25_forward to control forwarding.

echo "1" > /proc/sys/net/x25/x25_forward 
To turn on x25_forwarding, defaults to off
Requires the previous patch.

Signed-off-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/x25.h b/include/net/x25.h
index 3b11905..fc3f03d 100644
--- a/include/net/x25.h
+++ b/include/net/x25.h
@@ -180,6 +180,7 @@
 extern int  sysctl_x25_reset_request_timeout;
 extern int  sysctl_x25_clear_request_timeout;
 extern int  sysctl_x25_ack_holdback_timeout;
+extern int  sysctl_x25_forward;
 
 extern int  x25_addr_ntoa(unsigned char *, struct x25_address *,
 			  struct x25_address *);