message: updating how kernel variables are initialization in test description
diff: ///
  /// REDUCE_STRUCT kernel reference implementation:
  ///
  -/// Real_type xsum; Real_type ysum;
  -/// Real_type xmin; Real_type ymin;
  -/// Real_type xmax; Real_type ymax;
  +/// Real_type xsum = m_sum_init; Real_type ysum = m_sum_init;
  +/// Real_type xmin = m_min_init; Real_type ymin = m_min_init;
  +/// Real_type xmax = m_max_init; Real_type ymax = m_max_init;
  ///
  /// for (Index_type i = ibegin; i < iend; ++i ) {
  