Mcast rewrite no memcpy

use a 32bit mask in the adjacency to AND with the IP address and OR into the rewrite.

Change-Id: I80b0f246c18fd74f3e43c5d49e25833412f34665
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/adj/adj.c b/src/vnet/adj/adj.c
index f3d483a..9a01e89 100644
--- a/src/vnet/adj/adj.c
+++ b/src/vnet/adj/adj.c
@@ -360,7 +360,7 @@
 }
 
 /**
- * @brief Return the link type of the adjacency
+ * @brief Return the rewrite string of the adjacency
  */
 const u8*
 adj_get_rewrite (adj_index_t ai)