Atomic extensions

AtomicArc: A lightweight atomic pointer to Arc.

Example

use std::sync::{atomic::Ordering, Arc},

use atomic_ext::AtomicArc;

let a = Arc::new(1);
let x = AtomicArc::new(a);
let b = x.load(Ordering::Acquire);
let c = x.swap(Some(Arc::new(2)), Ordering::AcqRel);