sctp: Add socket option operation for Auto-ASCONF.

This patch allows the application to operate Auto-ASCONF on/off
behavior via setsockopt() and getsockopt().

Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sctp/user.h b/include/net/sctp/user.h
index 32fd512..0842ef0 100644
--- a/include/net/sctp/user.h
+++ b/include/net/sctp/user.h
@@ -92,6 +92,7 @@
 #define SCTP_LOCAL_AUTH_CHUNKS	27	/* Read only */
 #define SCTP_GET_ASSOC_NUMBER	28	/* Read only */
 #define SCTP_GET_ASSOC_ID_LIST	29	/* Read only */
+#define SCTP_AUTO_ASCONF       30
 
 /* Internal Socket Options. Some of the sctp library functions are
  * implemented using these socket options.