progress-bar: get screen width on windows

    struct winsize ts;

    if(!ioctl(STDIN_FILENO, TIOCGWINSZ, &ts))

      cols = ts.ws_col;

#elif defined(_WIN32)

    {

      HANDLE  stderr_hnd = GetStdHandle(STD_ERROR_HANDLE);

      CONSOLE_SCREEN_BUFFER_INFO console_info;

      if((stderr_hnd != INVALID_HANDLE_VALUE) &&

         GetConsoleScreenBufferInfo(stderr_hnd, &console_info)) {

        /*

         * Do not use +1 to get the true screen-width since writing a

         * character at the right edge will cause a line wrap.

         */

        cols = (int)

          (console_info.srWindow.Right - console_info.srWindow.Left);

      }

    }

#endif /* TIOCGSIZE */

    bar->width = cols;

  }