Fix variable does not need to be mutable warning for aio test
This fixes the following warning during run of cargo test
warning: variable does not need to be mutable
--> test/sys/test_aio.rs:16:13
|
16 | fn poll_aio(mut aiocb: &mut AioCb) -> Result<()> {
|             ^^^^^^^^^
|
= note: #[warn(unused_mut)] on by default
@@ -13,7 +13,7 @@ use std::{thread, time};
use tempfile::tempfile;
// Helper that polls an AioCb for completion or error
-fn poll_aio(mut aiocb: &mut AioCb) -> Result<()> {
+fn poll_aio(aiocb: &mut AioCb) -> Result<()> {
loop {
let err = aiocb.error();
if err != Err(Error::from(Errno::EINPROGRESS)) { return err; };
