Function rounding_shift_right_upward

src/opr/test/basic_arith/elemwise.cpp:119–123

template <typename T>
T rounding_shift_right_upward(T x, int k) {
    T mask = (T(1) << k) - 1;
    T threshold = mask >> 1;
    return (x >> k) + ((x & mask) > threshold);
}

template <typename T>
T do_round_mulh_saturate(T a, T b) {