misc: Break the big IP header files to improve compile time

Type: refactor

Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
Change-Id: Id1801519638a9b97175847d7ed58824fb83433d6
diff --git a/src/vnet/ip/icmp6.h b/src/vnet/ip/icmp6.h
index 628d225..7a5eef5 100644
--- a/src/vnet/ip/icmp6.h
+++ b/src/vnet/ip/icmp6.h
@@ -15,6 +15,8 @@
 #ifndef included_vnet_icmp6_h
 #define included_vnet_icmp6_h
 
+#include <vnet/ip/icmp46_packet.h>
+
 #define foreach_icmp6_error                                             \
   _ (NONE, "valid packets")                                             \
   _ (UNKNOWN_TYPE, "unknown type")                                      \