[IPV6]: ROUTE: Add accept_ra_defrtr sysctl.

This controls whether we accept default router information
in RAs.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ipv6.h

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 9c8f4c9..c5131a02 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -145,6 +145,7 @@
 	__s32		max_desync_factor;
 #endif
 	__s32		max_addresses;
+	__s32		accept_ra_defrtr;
 	void		*sysctl;
 };
 
@@ -167,6 +168,7 @@
 	DEVCONF_MAX_DESYNC_FACTOR,
 	DEVCONF_MAX_ADDRESSES,
 	DEVCONF_FORCE_MLD_VERSION,
+	DEVCONF_ACCEPT_RA_DEFRTR,
 	DEVCONF_MAX
 };