The local types.h must be include before standard includes.

It defines _GNU_SOURCE, which is needed on Linux for some
includes.

gtests/net/packetdrill/packet.h

@@ -26,11 +26,11 @@
 #ifndef __PACKET_H__
 #define __PACKET_H__
 
+#include "types.h"
+
 #include <stddef.h>
 #include <sys/time.h>
 
-#include "types.h"
-
 #include "assert.h"
 #include "gre.h"
 #include "header.h"