Move rfc6126_compatible into struct buffered.

interface.c

@@ -445,10 +445,7 @@ interface_up(struct interface *ifp, int up)
                     "but timestamps are disabled on interface %s.\n",
                     ifp->name);
 
-        if(IF_CONF(ifp, rfc6126) == CONFIG_YES)
-            ifp->flags |= IF_RFC6126;
-        else
-            ifp->flags &= ~IF_RFC6126;
+        ifp->buf.rfc6126_compatible = (IF_CONF(ifp, rfc6126) == CONFIG_YES);
 
         rc = check_link_local_addresses(ifp);
         if(rc < 0) {

interface.h

@@ -72,8 +72,6 @@ struct interface_conf {
 #define IF_FARAWAY (1 << 4)
 /* Send most TLVs over unicast. */
 #define IF_UNICAST (1 << 5)
-/* Remain compatible with RFC 6126. */
-#define IF_RFC6126 (1 << 6)
 
 /* Only INTERFERING can appear on the wire. */
 #define IF_CHANNEL_UNKNOWN 0
@@ -88,6 +86,7 @@ struct buffered {
     int flush_interval;
     struct timeval timeout;
     char enable_timestamps;
+    char rfc6126_compatible;
     char have_id;
     char have_nh;
     char have_prefix;