Fix memory crate test compile.

crate/memory/src/paging/mock_page_table.rs

@@ -133,7 +133,7 @@ impl MockPageTable {
 #[cfg(test)]
 mod test {
     use super::*;
-    use alloc::arc::Arc;
+    use alloc::sync::Arc;
     use core::cell::RefCell;
 
     #[test]

crate/memory/src/swap/mock_swapper.rs

@@ -1,5 +1,5 @@
 use super::Swapper;
-use alloc::btree_map::BTreeMap;
+use alloc::collections::BTreeMap;
 use core::mem::uninitialized;
 
 const PAGE_SIZE: usize = 4096;

crate/memory/src/swap/mod.rs

@@ -135,7 +135,7 @@ impl<T: PageTable, M: SwapManager, S: Swapper> DerefMut for SwapExt<T, M, S> {
 mod test {
     use super::*;
     use super::mock_swapper::MockSwapper;
-    use alloc::{arc::Arc, boxed::Box};
+    use alloc::{sync::Arc, boxed::Box};
     use core::cell::RefCell;
     use paging::MockPageTable;