apply fix for merge sort from issue #1163 by @jtfrey and re-enable it

#define PRId64 "ld"

#endif

// favor qsort over mergesort for stable release

// TODO: to be removed after stable release

#ifndef LMP_QSORT

#define LMP_QSORT

#endif

namespace LAMMPS_NS {

// enum used for KOKKOS host/device flags

    int *tmp = dest; dest = hold; hold = tmp;

    // merge from hold array to destiation array

    // merge from hold array to destination array

    for (i=0; i < num-1; i += 2*chunk) {

      j = i + 2*chunk;

      if (m > num) m=num;

      do_merge(dest,hold,i,m,m,j,ptr,comp);

    }

    // copy all indices not handled by the chunked merge sort loop

    for ( ; i < num ; i++ ) dest[i] = hold[i];

    chunk *= 2;

  }