message: make printing return place less verbose
diff: @@ -282,7 +282,7 @@ pub fn eval_main<'a, 'tcx: 'a>(
  for (i, frame) in ecx.stack().iter().enumerate() {
  trace!("-------------------");
  trace!("Frame {}", i);
  - trace!(" return: {:#?}", frame.return_place);
  + trace!(" return: {:?}", frame.return_place.map(|p| *p));
  for (i, local) in frame.locals.iter().enumerate() {
  trace!(" local {}: {:?}", i, local.value);
  }
  