zebra: Clean remote FDB entries upon VNI removal

When the VLAN-VNI mapping is configured via a map and not using
individual VXLAN interfaces, upon removal of a VNI ensure that the
remote FDB entries are uninstalled correctly.

Signed-off-by: Vivek Venkatraman <vivek@nvidia.com>

Ticket: #2613048
Reviewed By:
Testing Done:
1. Manual verification - logs in the ticket
2. Precommit (user job FRRouting#171) and evpn-min (user job FRRouting#170)

zebra/zebra_vxlan_if.c

@@ -785,9 +785,14 @@ int zebra_vxlan_if_vni_table_add_update(struct interface *ifp,
 
  /* release kernel deleted vnis */
  if (old_vni_table) {
- if (hashcount(old_vni_table))
- hash_iterate(old_vni_table, zebra_vxlan_if_vni_clean,
- zif);
+ if (hashcount(old_vni_table)) {
+ /* UGLY HACK: Put back the old table so that delete of
+ * MACs goes through and then flip back.
+ */
+ vni_info->vni_table = old_vni_table;
+ hash_iterate(old_vni_table, zebra_vxlan_if_vni_clean, zif);
+ vni_info->vni_table = vni_table;
+ }
  zebra_vxlan_vni_table_destroy(old_vni_table);
  }