epoch: Use std::sync::OnceLock instead of our own OnceLock

crossbeam-epoch/src/default.rs

@@ -8,7 +8,7 @@ use crate::collector::{Collector, LocalHandle};
 use crate::guard::Guard;
 use crate::primitive::thread_local;
 #[cfg(not(crossbeam_loom))]
-use crate::sync::once_lock::OnceLock;
+use std::sync::OnceLock;
 
 fn collector() -> &'static Collector {
     #[cfg(not(crossbeam_loom))]

crossbeam-epoch/src/sync/mod.rs

@@ -1,7 +1,4 @@
 //! Synchronization primitives.
 
 pub(crate) mod list;
-#[cfg(feature = "std")]
-#[cfg(not(crossbeam_loom))]
-pub(crate) mod once_lock;
 pub(crate) mod queue;