Fix CI for drop_guard

Author: yoshuawuyts

library/core/src/mem/drop_guard.rs

@@ -1,6 +1,6 @@
-use core::mem::ManuallyDrop;
-use core::ops::{Deref, DerefMut};
-use core::ptr;
+use crate::mem::ManuallyDrop;
+use crate::ops::{Deref, DerefMut};
+use crate::ptr;
 
 /// Wrap a value and run a closure when dropped.
 ///
@@ -52,10 +52,7 @@ where
     /// ```
     #[unstable(feature = "drop_guard", issue = "none")]
     pub fn new(inner: T, f: F) -> Self {
-        Self {
-            inner: ManuallyDrop::new(inner),
-            f: ManuallyDrop::new(f),
-        }
+        Self { inner: ManuallyDrop::new(inner), f: ManuallyDrop::new(f) }
     }
 
     /// Consumes the `Guard`, returning the wrapped value.
@@ -141,8 +138,9 @@ where
 // tests copied from https://docs.rs/scopeguard/latest/src/scopeguard/lib.rs.html#1-595
 #[cfg(test)]
 mod tests {
+    use crate::cell::Cell;
+
     use super::*;
-    use std::cell::Cell;
 
     #[test]
     fn test_only_dropped_by_closure_when_run() {