message: Update optimized_ops.h
  Use GetReciprocal to replace the 1/(1+x) logic.
diff: @@ -4384,18 +4384,9 @@ inline void Softmax(const SoftmaxParams& params,
  // Compute the fixed-point multiplier and shift that we need to apply to
  // perform a division by the above-computed sum-of-exponentials.
  - int32 fixed_sum_of_exps = sum_of_exps.raw();
  - int headroom_plus_one =
  - CountLeadingZeros(static_cast<uint32>(fixed_sum_of_exps));
  - // This is the number of bits to the left of the binary point above 1.0.
  - // Consider fixed_sum_of_exps=1.25. In that case shifted_scale=0.8 and
  - // no later adjustment will be needed.
  - int num_bits_over_unit = kAccumulationIntegerBits - headroom_plus_one;
  - int32 shifted_sum_minus_one = static_cast<int32>(
  - (static_cast<uint32>(fixed_sum_of_exps) << headroom_plus_one) -
  - (static_cast<uint32>(1) << 31));
  - FixedPoint0 shifted_scale = gemmlowp::one_over_one_plus_x_for_x_in_0_1(
  - FixedPoint0::FromRaw(shifted_sum_minus_one));
  + int num_bits_over_unit = 0;
  + FixedPoint0 shifted_scale = FixedPoint0::FromRaw(GetReciprocal(
  + sum_of_exps.raw(), kAccumulationIntegerBits, &num_bits_over_unit));
  // Compute the quotients of exponentials of differences of entries in the
  // current row from the largest entry, over the previously-computed sum of
  