features: don't break linked list, create separate one for arc

We need to keep original linked list so destructire can remove entries.

Change-Id: I5ff5ca0e1a417d88707255207725bba46433c943
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vnet/feature/feature.h b/src/vnet/feature/feature.h
index 70a456e..f6b1d12 100644
--- a/src/vnet/feature/feature.h
+++ b/src/vnet/feature/feature.h
@@ -43,7 +43,7 @@
 typedef struct _vnet_feature_registration
 {
   /** next registration in list of all registrations*/
-  struct _vnet_feature_registration *next;
+  struct _vnet_feature_registration *next, *next_in_arc;
   /** Feature arc name */
   char *arc_name;
   /** Graph node name */