Warn about useless matches

Clippy should warn about this useless match:

```rust
fn main()
{
    let a = 1;
    let b = 2;
    let c = 3;
    
    match (a, b, c) {
        (x, y, z) => {
            // this is a useless match
        }
    }
}
```

cc @oli-obk 