remove unnecessary transmutes

src/libstd/unstable/atomics.rs

@@ -339,13 +339,7 @@ impl<T> AtomicOption<T> {
 #[unsafe_destructor]
 impl<T> Drop for AtomicOption<T> {
     fn drop(&mut self) {
-        // This will ensure that the contained data is
-        // destroyed, unless it's null.
-        unsafe {
-            // FIXME(#4330) Need self by value to get mutability.
-            let this : &mut AtomicOption<T> = cast::transmute(self);
-            let _ = this.take(SeqCst);
-        }
+        let _ = self.take(SeqCst);
     }
 }