message: ODR-define bfloat16::NAN_VALUE and ZERO_VALUE.
  These were missing proper definitions, so if they were ever ODR-used, you'd get
  a link error.
diff: @@ -19,6 +19,9 @@ limitations under the License.
  namespace tensorflow {
  +const uint16_t bfloat16::NAN_VALUE;
  +const uint16_t bfloat16::ZERO_VALUE;
  +
  B16_DEVICE_FUNC bfloat16::operator Eigen::half() const {
  return static_cast<Eigen::half>(float(*this));
  }
  