ipv6: introduce IFA_F_STABLE_PRIVACY flag

We need to mark appropriate addresses so we can do retries in case their
DAD failed.

Cc: Erik Kline <ek@google.com>
Cc: Fernando Gont <fgont@si6networks.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: YOSHIFUJI Hideaki/吉藤英明 <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_addr.h

@@ -51,6 +51,7 @@ enum {
 #define IFA_F_MANAGETEMPADDR	0x100
 #define IFA_F_NOPREFIXROUTE	0x200
 #define IFA_F_MCAUTOJOIN	0x400
+#define IFA_F_STABLE_PRIVACY	0x800
 
 struct ifa_cacheinfo {
 	__u32	ifa_prefered;