IP Multicast FIB (mfib)

 - IPv[46] mfib tables with support for (*,G/m), (*,G) and (S,G) exact and longest prefix match
 - Replication represented via a new replicate DPO.
 - RPF configuration and data-plane checking
 - data-plane signals sent to listening control planes.

The functions of multicast forwarding entries differ from their unicast conterparts, so we introduce a new mfib_table_t and mfib_entry_t objects. However, we re-use the fib_path_list to resolve and build the entry's output list. the fib_path_list provides the service to construct a replicate DPO for multicast.

'make tests' is added to with two new suites; TEST=mfib, this is invocation of the CLI command 'test mfib' which deals with many path add/remove, flag set/unset scenarios, TEST=ip-mcast, data-plane forwarding tests.

Updated applications to use the new MIFB functions;
  - IPv6 NS/RA.
  - DHCPv6
 unit tests for these are undated accordingly.

Change-Id: I49ec37b01f1b170335a5697541c8fd30e6d3a961
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/fib/fib_node.h b/src/vnet/fib/fib_node.h
index 3ad8ee9..457dfb7 100644
--- a/src/vnet/fib/fib_node.h
+++ b/src/vnet/fib/fib_node.h
@@ -31,6 +31,7 @@
      */
     FIB_NODE_TYPE_WALK,
     FIB_NODE_TYPE_ENTRY,
+    FIB_NODE_TYPE_MFIB_ENTRY,
     FIB_NODE_TYPE_PATH_LIST,
     FIB_NODE_TYPE_PATH,
     FIB_NODE_TYPE_ADJ,
@@ -51,6 +52,7 @@
 
 #define FIB_NODE_TYPES {                          \
     [FIB_NODE_TYPE_ENTRY]     = "entry",          \
+    [FIB_NODE_TYPE_MFIB_ENTRY] = "mfib-entry",    \
     [FIB_NODE_TYPE_WALK]      = "walk",           \
     [FIB_NODE_TYPE_PATH_LIST] = "path-list",      \
     [FIB_NODE_TYPE_PATH]      = "path",           \