USER-DPD: Use subphases when processing AIR zero (locals) in SSA.

  // process neighbors in the local AIR

  while (ii < inum) {

    i = ilist[ii];

    int len = list->numneigh[i];

    if (useDPDE) ssa_update_dpde(i, &(list->firstneigh[i][0]), len);

    else ssa_update_dpd(i, &(list->firstneigh[i][0]), len);

    for (int subphase = 0; subphase < 4; subphase++) {

      int start = (subphase > 0) ? list->ndxAIR_ssa[i][subphase - 1] : 0;

      int len = list->ndxAIR_ssa[i][subphase] - start;

      if (len > 0) {

        if (useDPDE) ssa_update_dpde(i, &(list->firstneigh[i][start]), len);

        else ssa_update_dpd(i, &(list->firstneigh[i][start]), len);

      }

    }

    ii++;

  }