message: Make kMaxBatchCount constexpr.
  Also define it to avoid link error. Resolves a TODO.
diff: @@ -3338,9 +3338,7 @@ class CUDABlasLtMatmulPlan final : public blas::IBlasLtMatmulPlan {
  private:
  // In some cases cublasLt does not support large batch sizes, so we need to
  // split up such cases into multiple calls.
  - // TODO(reedwm): Making this static or constexpr causes a link error with gcc
  - // in debug mode for unknown reasons. Investigate why.
  - const int kMaxBatchCount = 65535;
  + static constexpr int kMaxBatchCount = 65535;
  blas::BlasLtMatmulPlanParams params_;
  blas::DataType scale_type_;
  UniqueOpDesc op_desc_;
  @@ -3358,6 +3356,8 @@ class CUDABlasLtMatmulPlan final : public blas::IBlasLtMatmulPlan {
  UniqueLayoutDesc d_remainder_desc_;
  };
  +/*static*/ constexpr int CUDABlasLtMatmulPlan::kMaxBatchCount;
  +
  bool CUDABlasLtMatmulPlan::SetBiasPointer(const void *bias) const {
  return SetCublasLtAttr(op_desc_.get(), CUBLASLT_MATMUL_DESC_BIAS_POINTER,
  bias)
  