bug#6600: [PATCH] sort: add --threads option to parallelize internal sort.

[Pádraig Brady]

Here's a small cleanup I missed.
Alternatively one could make heap() return NULL rather than aborting,
but since it already used xmalloc, I'm tending to this..

commit cec33eb226df63f406f7eb70cd46d960ee02a060
Author: Pádraig Brady <p...@draigbrady.com>
Date:   Tue Jul 13 08:23:52 2010 +0100

    maint: heap.c: simplify heap_alloc

    * gl/lib/heap.c (heap_alloc): Use the fact that the xalloc
    routines will not return NULL.  Also remove the redundant
    temporary variables.

diff --git a/gl/lib/heap.c b/gl/lib/heap.c
index a37224f..f148434 100644
--- a/gl/lib/heap.c
+++ b/gl/lib/heap.c
@@ -36,22 +36,12 @@ static void heapify_up (void **, size_t,
 struct heap *
 heap_alloc (int (*compare)(const void *, const void *), size_t n_reserve)
 {
-  struct heap *heap;
-  void *xmalloc_ret = xmalloc (sizeof *heap);
-  heap = (struct heap *) xmalloc_ret;
-  if (!heap)
-    return NULL;
+  struct heap *heap = xmalloc (sizeof *heap);

-  if (n_reserve <= 0)
+  if (n_reserve == 0)
     n_reserve = 1;

-  xmalloc_ret = xmalloc (n_reserve * sizeof *(heap->array));
-  heap->array = (void **) xmalloc_ret;
-  if (!heap->array)
-    {
-      free (heap);
-      return NULL;
-    }
+  heap->array = xmalloc (n_reserve * sizeof *(heap->array));

   heap->array[0] = NULL;
   heap->capacity = n_reserve;
@@ -84,8 +74,7 @@ heap_insert (struct heap *heap, void *item)
   if (heap->capacity - 1 <= heap->count)
     {
       size_t new_size = (2 + heap->count) * sizeof *(heap->array);
-      void *realloc_ret = xrealloc (heap->array, new_size);
-      heap->array = (void **) realloc_ret;
+      heap->array = xrealloc (heap->array, new_size);