Loxigen: added src/dst meta id matches

Encode a 1 byte src and 1 byte dst 'meta' ID into
ofp_match's pad2 byte.
diff --git a/test_data/of10/flow_add.data b/test_data/of10/flow_add.data
index 9801a36..42fca89 100644
--- a/test_data/of10/flow_add.data
+++ b/test_data/of10/flow_add.data
@@ -42,6 +42,8 @@
     eth_type = 0x0,
     ip_dscp = 0x0,
     ip_proto = 0x0,
+    src_meta_id = 0x0,
+    dst_meta_id = 0x0,
     ipv4_src = 192.168.3.127,
     ipv4_dst = 255.255.255.255,
     tcp_src = 0x0,