Separate heap for IPv4 mtries

Change-Id: I497e9f6489dd35219bcf2b51ac992467aac4c8eb
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/ip/ip4.h b/src/vnet/ip/ip4.h
index 4c5cc05..f7e5fe3 100644
--- a/src/vnet/ip/ip4.h
+++ b/src/vnet/ip/ip4.h
@@ -148,6 +148,12 @@
 
     u8 pad[2];
   } host_config;
+
+  /** Heapsize for the Mtries */
+  uword mtrie_heap_size;
+
+  /** The memory heap for the mtries */
+  void *mtrie_mheap;
 } ip4_main_t;
 
 /** Global ip4 main structure. */