Custom route attributes

For local route marking purposes, local custom route attributes may be
defined. These attributes are seamlessly stripped after export filter to
every real protocol like Kernel, BGP or OSPF, they however pass through
pipes. We currently allow at most 256 custom attributes.

This should be much faster than currently used bgp communities
for marking routes.

filter/filter.c

@@ -1063,7 +1063,7 @@ interpret(struct f_inst *what)
 	break;
       }
 
-      switch (what->aux & EAF_TYPE_MASK) {
+      switch (e->type & EAF_TYPE_MASK) {
       case EAF_TYPE_INT:
 	res.type = f_type;
 	res.val.i = e->u.data;