Function `ninther`

pub(in ::slice::sort::select) fn ninther<T, F: FnMut(&T, &T) -> bool>(v: &mut [T], is_less: &mut F, a: usize, b: usize, c: usize, d: usize, e: usize, f: usize, g: usize, h: usize, i: usize)

Moves around the 9 elements at the indices a..i, such that v[d] contains the median of the 9 elements and the other elements are partitioned around it.