void mutt_qsort_r(void *base, size_t nmemb, size_t size, qsort_r_compar_t compar, void *arg)
Sort an array, where the comparator has access to opaque data rather than requiring global variables.
int(* qsort_r_compar_t)(const void *a, const void *b, void *arg)
Prototype for generic comparison function, compatible with qsort_r()