heapsort
int heapsort(void *, size_t, size_t, int (*)(const void *, const void *));
PROTO_NORMAL(heapsort);
DEF_WEAK(heapsort);
if (heapsort(a, n, es, cmp) == 0)
heapsort(list->list, list->count,
#define DEFAULT_SORT_FUNC heapsort