message: Add dummy MaskedArray constr with single param
diff: @@ -1365,6 +1365,7 @@ struct MaskedArray : ArrayBase<value_t<T>, is_mask_v<T>, MaskedArray<T>> {
  static constexpr bool IsMaskedArray = true;
  MaskedArray() = default;
  + template <typename T2> MaskedArray(T2) { }
  MaskedArray(T &d, const Mask &m) : d(&d), m(m) { }
  ENOKI_INLINE void operator=(const MaskedArray<T> &value) { d = value.d; m = value.m; }
  