Add snooping of DHCPv6 prefix delegation to the DHCP-relay function.

src/dhcp6-protocol.h

@@ -55,6 +55,8 @@
 #define OPTION6_RECONF_ACCEPT   20
 #define OPTION6_DNS_SERVER      23
 #define OPTION6_DOMAIN_SEARCH   24
+#define OPTION6_IA_PD           25
+#define OPTION6_IAPREFIX        26
 #define OPTION6_REFRESH_TIME    32
 #define OPTION6_REMOTE_ID       37
 #define OPTION6_SUBSCRIBER_ID   38