qsort_r
extern void qsort_r(void* base, size_t numElements, size_t sizeOfElement,
qsort_r(base, nmemb, size, compar, compard);
qsort_r(base, nmemb, size, &d, solv_sort_helper);
(qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)