message: Initialize object variables in HLO evaluator.
  The lack of initialization of the dynamic_dimension_inference_ member was causing random crashes when used from a PT client.
diff: @@ -331,16 +331,16 @@ class HloEvaluator : public DfsHloVisitorWithDefault {
  std::vector<const Literal*> arg_literals_;
  // Max loop iterations to execute with no maximum if negative.
  - int64 max_loop_iterations_;
  + int64 max_loop_iterations_ = 0;
  // Module-level seed handle.
  - uint64 seed_;
  + uint64 seed_ = 0;
  // RNG engine.
  std::minstd_rand0 engine_;
  // DynamicDimensionInference is used to evaluate GetDimensionSize, which
  // returns the dynamic dimension size of its operand.
  - DynamicDimensionInference* dynamic_dimension_inference_;
  + DynamicDimensionInference* dynamic_dimension_inference_ = nullptr;
  // Optional handler for custom_call ops.
  std::function<StatusOr<Literal>(HloInstruction* custom_call,
  