memmem, bytestring: Fix includes in _info

When I fixed up the includes in _info for nearly everything, I managed to
leave out a couple of my own modules.  This fixes them up.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

ccan/bytestring/_info

+#include "config.h"
 #include <stdio.h>
 #include <string.h>
-#include "config.h"
 
 /**
  * bytestring - simple bytestring handling

ccan/memmem/_info

-#include <string.h>
 #include "config.h"
+#include <stdio.h>
+#include <string.h>
 
 /**
  * memmem - Trivial module providing a memmem() implementation