include config.h before all system headers, so that _FILE_OFFSET_BITS and

similar is set properly by us first

tests/libtest/test.h

-#include <curl.h>
-#include <stdio.h>
-#include <string.h>
-
 #ifdef HAVE_CONFIG_H
 /* Now include the config.h file from libcurl's private libdir, so that we
    get good in-depth knowledge about the system we're building this on */
 #include "config.h"
 #endif
 
+#include <curl.h>
+#include <stdio.h>
+#include <string.h>
+
 extern char *arg2; /* set by first.c to the argv[2] or NULL */