Fix some bad code in mysqltest.c which cause segfault

client/mysqltest.c:
  Remove vsnprintf() and DBUG_PRINT from die() function, as it's not portable to Windows, and it's not allowed to
  call vsnprintf() and then vfprintf() with the same args.
  Can't just print the buffer here, because the buffer is a fixed size.
  If the message is longer than will fit int he buffer, it would get
  truncated on Unix, and the full thing would be printed on Windows.
  This DBUG_PRINT isn't important enough for this hassle, so just get rid
  of it.

client/mysqltest.c

@@ -727,13 +727,6 @@ void die(const char *fmt, ...)
   va_start(args, fmt);
   if (fmt)
   {
-#ifdef DBUG_ON
-#ifndef __WIN__
-    char buff[256];
-    vsnprintf(buff, sizeof(buff), fmt, args);
-    DBUG_PRINT("error", ("%s", buff));
-#endif
-#endif
     fprintf(stderr, "mysqltest: ");
     if (cur_file && cur_file != file_stack)
       fprintf(stderr, "In included file \"%s\": ",