Remove another needless pass by value
Remove another needless pass by value

warning: this argument is passed by value, but not consumed in the
function body
   --> src/squeeze.rs:351:47
    |
351 | fn trace_backwards(size: usize, length_array: Vec<u16>) ->
Vec<u16> {
    |                                               ^^^^^^^^ help:
consider changing the type to `&[u16]`
    |
    = note: #[warn(needless_pass_by_value)] on by default
    = help: for further information visit
https://github.com/Manishearth/rust-clippy/wiki#needless_pass_by_value

carols10cents/zopfli,carols10cents/zopfli