Function par_quicksort

pub(super) fn par_quicksort<T, F>(v: &mut [T], is_less: F)
where
    T: Send,
    F: Fn(&T, &T) -> bool + Sync,

Sorts v using pattern-defeating quicksort in parallel.

The algorithm is unstable, in-place, and O(n * log(n)) worst-case.