Add impl<T> AsMut<T> for Exclusive<T>

Author: Jules-Bertholet

library/core/src/sync/exclusive.rs

@@ -250,6 +250,17 @@ where
     }
 }
 
+#[unstable(feature = "exclusive_wrapper", issue = "98407")]
+impl<T> AsMut<T> for Exclusive<T>
+where
+    T: ?Sized,
+{
+    #[inline(always)]
+    fn as_mut(&mut self) -> &mut T {
+        self.get_mut()
+    }
+}
+
 #[unstable(feature = "exclusive_wrapper", issue = "98407")]
 impl<T> Clone for Exclusive<T>
 where