remove ifdefs for selecting between plain and hybrid merge sort. use hybrid only.

// for improved performance, we employ an in-place insertion sort on

// chunks of up to 64 elements and switch to merge sort from then on.

// compile with -DLMP_USE_MERGE_SORT to switch to a plain merge sort

#if !defined(LMP_USE_MERGE_SORT) && !defined(LMP_USE_HYBRID_SORT)

#define LMP_USE_HYBRID_SORT

#endif

#if defined(LMP_USE_HYBRID_SORT)

// part 1. insertion sort for pre-sorting of small chunks

static void insertion_sort(int *index, int num, void *ptr,

    }

  }

}

#endif

// part 2. merge two sublists

  int chunk,i,j;

#if defined(LMP_USE_HYBRID_SORT)

  // do insertion sort on chunks of up to 64 elements

  chunk = 64;

  if (chunk >= num) return;

#else

  chunk = 1;

#endif

  // continue with merge sort on the pre-sorted chunks.

  // we need an extra buffer for temporary storage and two

  // pointers to operate on, so we can swap the pointers