Too much space for stack

[sebawild]

Unlikely to be a big performance issue, but the stack space seems to be $n$, whereas $\log_2(n)+c$ is enough (for a small $c$ I don't know from the top of my head, but $c =4$ should do.)

powersort/src/powersort_final.rs

Line 237 in e184bed

let mut runs: Vec<Run> = Vec::with_capacity(capacity(n));