Added missing include for stdio

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404351

test/testnative.c

 /* Simple program:  Create a native window and attach an SDL renderer */
 
+#include <stdio.h>
+
 #include "testnative.h"
 
 #define WINDOW_W    640