### What it does
Checks for calls to `std::mem::forget` with a reference
instead of an owned value.

### Why is this bad?
Calling `forget` on a reference will only forget the
reference itself, which is a no-op. It will not forget the underlying
referenced
value, which is likely what was intended.

### Example
```
let x = Box::new(1);
std::mem::forget(&x) // Should have been forget(x), x will still be dropped
```