message: stdio: add support for %o to printf()
diff: @@ -85,6 +85,13 @@ pub unsafe fn printf<W: fmt::Write>(mut w: W, format: *const c_char, mut ap: VaL
  found_percent = false;
  }
  + 'o' => {
  + let a = ap.get::<c_uint>();
  +
  + w.write_fmt(format_args!("{:o}", a));
  +
  + found_percent = false;
  + }
  '-' => {}
  '+' => {}
  ' ' => {}
  