AtomicOption should run Box::drop on drop.

[quadrupleslap]

Right now it's leaking memory and not running destructors. This is necessary:

impl<T> Drop for AtomicOption<T> {
    fn drop(&mut self) {
        let inner = self.inner.load(Ordering::SeqCst);
        if !inner.is_null() {
            unsafe { Box::from_raw(inner); }
        }
    }
}

Playground: https://is.gd/FUK0pr

[spacejam]

just hit this while sanitizing for leaks...

[spacejam]

mostly copied your code but SeqCst -> Relaxed because drop shouldn't get reordered before another thread's access.

#153