message: Implement intrinsic arith_offset
diff: @@ -379,6 +379,14 @@ pub fn codegen_call<'a, 'tcx: 'a>(
  "assume" => {
  assert_eq!(args.len(), 1);
  }
  + "arith_offset" => {
  + assert_eq!(args.len(), 2);
  + let base = args[0].load_value(fx);
  + let offset = args[1].load_value(fx);
  + let res = fx.bcx.ins().iadd(base, offset);
  + let res = CValue::ByVal(res, ret.layout());
  + ret.write_cvalue(fx, res);
  + }
  "likely" | "unlikely" => {
  assert_eq!(args.len(), 1);
  ret.write_cvalue(fx, args[0]);
  