message: test pointer string formatting
diff: // compile-flags: -Zmiri-seed=0000000000000000
  fn main() {
  + // Some casting-to-int with arithmetic.
  let x = &42 as *const i32 as usize;
  let y = x * 2;
  assert_eq!(y, x + x);
  let z = y as u8 as usize;
  assert_eq!(z, y % 256);
  +
  + // Pointer string formatting! We can't check the output as it changes when libstd changes,
  + // but we can make sure Miri does not error.
  + format!("{:?}", &mut 13 as *mut _);
  }
  