Eliminate mut reference UB in Drop impl for Rc<T> This changes `self.ptr.as_mut()` with `get_mut_unchecked` which does not use an intermediate reference. Arc<T> already handled this case properly. Fixes #76509
Eliminate mut reference UB in Drop impl for Rc<T> This changes `self.ptr.as_mut()` with `get_mut_unchecked` which does not use an intermediate reference. Arc<T> already handled this case properly. Fixes #76509