message: Fixes warning about unused-but-set variables in Spio.
diff: @@ -135,7 +135,10 @@ void IOManager::write(sidre::DataGroup * datagroup, int num_files, const std::st
  datagroup->save(h5_group_id);
  - herr_t status = H5Gclose(h5_group_id);
  + herr_t status;
  + AXOM_DEBUG_VAR(status);
  +
  + status = H5Gclose(h5_group_id);
  SLIC_ASSERT(status >= 0);
  status = H5Fflush(h5_file_id, H5F_SCOPE_LOCAL);
  SLIC_ASSERT(status >= 0);
  @@ -231,6 +234,7 @@ void IOManager::readSidreHDF5(sidre::DataGroup * datagroup, const std::string& r
  int group_id = m_baton->wait();
  herr_t errv;
  + AXOM_DEBUG_VAR(errv);
  std::string hdf5_name = getHDF5FileName(file_pattern, root_file, group_id);
  @@ -276,6 +280,7 @@ void IOManager::loadExternalData(sidre::DataGroup * datagroup, const std::string
  int group_id = m_baton->wait();
  herr_t errv;
  + AXOM_DEBUG_VAR(errv);
  std::string hdf5_name = getHDF5FileName(file_pattern, root_file, group_id);
  @@ -561,7 +566,10 @@ void IOManager::writeGroupToRootFile(sidre::DataGroup * group,
  conduit::relay::io::hdf5_write(data_holder, group_id);
  - herr_t errv = H5Gclose(group_id);
  + herr_t errv;
  + AXOM_DEBUG_VAR(errv);
  +
  + errv = H5Gclose(group_id);
  SLIC_ASSERT(errv >= 0);
  errv = H5Fflush(root_file_id, H5F_SCOPE_LOCAL);
  @@ -606,7 +614,10 @@ void IOManager::writeGroupToRootFileAtPath(sidre::DataGroup * group,
  conduit::relay::io::hdf5_write(data_holder, group_id);
  - herr_t errv = H5Gclose(group_id);
  + herr_t errv;
  + AXOM_DEBUG_VAR(errv);
  +
  + errv = H5Gclose(group_id);
  SLIC_ASSERT(errv >= 0);
  errv = H5Fflush(root_file_id, H5F_SCOPE_LOCAL);
  @@ -644,7 +655,10 @@ void IOManager::writeViewToRootFileAtPath(sidre::DataView * view,
  conduit::relay::io::hdf5_write(data_holder, path_id);
  - herr_t errv = H5Fflush(root_file_id, H5F_SCOPE_LOCAL);
  + herr_t errv;
  + AXOM_DEBUG_VAR(errv);
  +
  + errv = H5Fflush(root_file_id, H5F_SCOPE_LOCAL);
  SLIC_ASSERT(errv >= 0);
  errv = H5Fclose(root_file_id);
  