IPVS: Allow configuration of persistence engines

Allow the persistence engine of a virtual service to be set, edited
and unset.

This feature only works with the netlink user-space interface.

Signed-off-by: Simon Horman <horms@verge.net.au>
Acked-by: Julian Anastasov <ja@ssi.bg>

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index a6b93a2..52fbe23 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -444,6 +444,7 @@
 
 	/* virtual service options */
 	char			*sched_name;
+	char			*pe_name;
 	unsigned		flags;		/* virtual service flags */
 	unsigned		timeout;	/* persistent timeout in sec */
 	u32			netmask;	/* persistent netmask */