Revert "DO NOT MERGE: Remove two almost-unused include files."

This reverts commit 86cb1ac3d69805bebcac7a18b408d656603028f4.

Change-Id: If592b80e8107f468c2fe1caf00fcff49f25a9441
diff --git a/ipv4.c b/ipv4.c
index 47f2422..89e47e4 100644
--- a/ipv4.c
+++ b/ipv4.c
@@ -28,6 +28,7 @@
 
 #include "translate.h"
 #include "checksum.h"
+#include "ipv4.h"
 #include "logging.h"
 #include "debug.h"
 #include "dump.h"