timer: use std::sync::atomic::AtomicU64 instead of own AtomicU64 (#1421)

tokio-timer/src/timer/entry.rs

@@ -1,11 +1,10 @@
-use crate::atomic::AtomicU64;
 use crate::timer::{HandlePriv, Inner};
 use crate::Error;
 use crossbeam_utils::CachePadded;
 use std::cell::UnsafeCell;
 use std::ptr;
-use std::sync::atomic::AtomicBool;
 use std::sync::atomic::Ordering::{Relaxed, SeqCst};
+use std::sync::atomic::{AtomicBool, AtomicU64};
 use std::sync::{Arc, Weak};
 use std::task::{self, Poll};
 use std::time::{Duration, Instant};

tokio-timer/src/timer/mod.rs

@@ -49,11 +49,10 @@ pub use self::handle::{with_default, Handle};
 pub use self::now::{Now, SystemNow};
 pub(crate) use self::registration::Registration;
 
-use crate::atomic::AtomicU64;
 use crate::wheel;
 use crate::Error;
-use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering::SeqCst;
+use std::sync::atomic::{AtomicU64, AtomicUsize};
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 use std::usize;