message: fix non-integer undefs
diff: @@ -50,7 +50,7 @@ void UndefValue::print(ostream &os) const {
  StateValue UndefValue::toSMT(State &s) const {
  auto name = getFreshName();
  - expr var = expr::mkVar(name.c_str(), bits());
  + expr var = expr::mkVar(name.c_str(), getType().getDummyValue());
  s.addUndefVar(var);
  return { move(var), true };
  }
  