PR#331: for Visual Studio, use a snprintf/vsnprintf wrapper that ensures the string is terminated.

tests/test_locale.c

@@ -7,6 +7,7 @@
 #include "config.h"
 #include "json.h"
 #include "json_tokener.h"
+#include "snprintf_compat.h"
 
 #ifdef HAVE_LOCALE_H
 #include <locale.h>