message: When partitioning a disconnected mesh with METIS 5, disable
  the option for contiguous partitions which generates an error.
diff: @@ -7025,6 +7025,11 @@ int *Mesh::CartesianPartitioning(int nxyz[])
  return partitioning;
  }
  +void FindPartitioningComponents(Table &elem_elem,
  + const Array<int> &partitioning,
  + Array<int> &component,
  + Array<int> &num_comp);
  +
  int *Mesh::GeneratePartitioning(int nparts, int part_method)
  {
  #ifdef MFEM_USE_METIS
  @@ -7106,6 +7111,15 @@ int *Mesh::GeneratePartitioning(int nparts, int part_method)
  #else
  METIS_SetDefaultOptions(options);
  options[METIS_OPTION_CONTIG] = 1; // set METIS_OPTION_CONTIG
  + // If the mesh is disconnected, disable METIS_OPTION_CONTIG.
  + {
  + Array<int> part(partitioning, NumOfElements);
  + part = 0; // single part for the whole mesh
  + Array<int> component; // size will be set to num. elem.
  + Array<int> num_comp; // size will be set to num. parts (1)
  + FindPartitioningComponents(*el_to_el, part, component, num_comp);
  + if (num_comp[0] > 1) { options[METIS_OPTION_CONTIG] = 0; }
  + }
  #endif
  // Sort the neighbor lists
  