add third batch of feedback from review

Author: yoshuawuyts

library/core/src/mem/drop_guard.rs

@@ -1,7 +1,6 @@
 use crate::fmt::{self, Debug};
 use crate::mem::ManuallyDrop;
 use crate::ops::{Deref, DerefMut};
-use crate::ptr;
 
 /// Wrap a value and run a closure when dropped.
 ///
@@ -88,7 +87,7 @@ where
         // Next we manually read the stored value from the guard.
         //
         // SAFETY: this is safe because we've taken ownership of the guard.
-        let value = unsafe { ptr::read(&*guard.inner) };
+        let value = unsafe { ManuallyDrop::take(&mut guard.inner) };
 
         // Finally we drop the stored closure. We do this *after* having read
         // the value, so that even if the closure's `drop` function panics,