Add an ip6 local hop-by-hop protocol demux table

Add a minimal ip6 hbh header processing test.

ioam plugin: use ip6_local_hop_by_hop_register_protocol() in
udp_ping_init().

Please test the ioam plugin udp_ping path AYEC, so I can
publish the patch.

Change-Id: I74e35276d6c38c31022026cfd238fad5e4a54485
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/src/vnet/ip/ip6.h b/src/vnet/ip/ip6.h
index 1a57c41..e66bbdd 100644
--- a/src/vnet/ip/ip6.h
+++ b/src/vnet/ip/ip6.h
@@ -388,6 +388,7 @@
 				       int *bogus_lengthp);
 
 void ip6_register_protocol (u32 protocol, u32 node_index);
+void ip6_local_hop_by_hop_register_protocol (u32 protocol, u32 node_index);
 
 serialize_function_t serialize_vnet_ip6_main, unserialize_vnet_ip6_main;