Suggest .clone() when moved while borrowed

tests/ui/pattern/move-ref-patterns/borrowck-move-ref-pattern.stderr

@@ -10,6 +10,11 @@ LL |     let [ref _x0_hold, _x1, ref xs_hold @ ..] = arr;
 LL |     _x1 = U;
 LL |     drop(hold_all);
    |          -------- borrow later used here
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |     let hold_all = &arr.clone();
+   |                        ++++++++
 
 error[E0384]: cannot assign twice to immutable variable `_x1`
   --> $DIR/borrowck-move-ref-pattern.rs:9:5