message: Updated group_bidirectional_sequence_ops.cc
  Fixed warning issues in the file
diff: @@ -135,7 +135,7 @@ bool CheckTwoUnidirectionalSequenceOpsAreValid(
  }
  // fw_lstm & bw_lstm should point to the same input, but reversed sequence.
  - for (int i = 0; i < first_fw_sequence_op_input->inputs.size(); ++i) {
  + for (size_t i = 0; i < first_fw_sequence_op_input->inputs.size(); ++i) {
  if (first_fw_sequence_op_input->inputs[i] !=
  first_bw_sequence_op_input
  ->inputs[first_fw_sequence_op_input->inputs.size() - i - 1]) {
  @@ -296,7 +296,7 @@ void RewireBidirectionalSequenceSequenceOpsConnections(
  }
  string cur_fw_input = input_array_name;
  string cur_bw_input = input_array_name;
  - for (int i = 0; i < bidirectional_sequence_ops.size(); ++i) {
  + for (size_t i = 0; i < bidirectional_sequence_ops.size(); ++i) {
  DeleteArrayIfUsedOnce(bidirectional_sequence_ops[i]->inputs[0], model);
  bidirectional_sequence_ops[i]->inputs[0] = cur_fw_input;
  if (i != 0) {
  @@ -329,7 +329,7 @@ void RewireFinalUnpackOutputs(const UnpackOperator& original_unpack_operator,
  (*final_unpack_operator)->axis = original_unpack_operator.axis;
  (*final_unpack_operator)->num = original_unpack_operator.num;
  - for (int i = 0; i < original_unpack_operator.outputs.size(); ++i) {
  + for (size_t i = 0; i < original_unpack_operator.outputs.size(); ++i) {
  const string& output_array_name = original_unpack_operator.outputs[i];
  const string& final_unpack_output_array_name = AvailableArrayName(
  *model, "bidirectional_sequence_unpack_" + std::to_string(i));
  