message: Fix impl_rem_assign_scalar for rust 1.8
diff: @@ -796,7 +796,7 @@ impl Rem<BigUint> for BigDigit {
  }
  macro_rules! impl_rem_assign_scalar {
  - ($scalar:ty, $to_scalar:tt) => {
  + ($scalar:ty, $to_scalar:ident) => {
  forward_val_assign_scalar!(impl RemAssign for BigUint, $scalar, rem_assign);
  impl<'a> RemAssign<&'a BigUint> for $scalar {
  #[inline]
  