Refactor vlib_buffer flags

Change-Id: I853386aebfe488ebb10328435b81b6e3403c5dd0
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vnet/dns/dns.c b/src/vnet/dns/dns.c
index 24cd596..eff8549 100644
--- a/src/vnet/dns/dns.c
+++ b/src/vnet/dns/dns.c
@@ -2803,7 +2803,7 @@
    * In the resolution-required / deferred case, resetting a freshly-allocated
    * buffer won't hurt. We hope.
    */
-  b0->flags &= VLIB_BUFFER_FREE_LIST_INDEX_MASK;
+  b0->flags &= VLIB_BUFFER_NON_DEFAULT_FREELIST;
   b0->flags |= (VNET_BUFFER_F_LOCALLY_ORIGINATED
 		| VLIB_BUFFER_TOTAL_LENGTH_VALID);
   b0->current_data = 0;