Pass --cfg clippy to clippy-driver

Author: GuillaumeGomez

src/driver.rs

@@ -271,7 +271,9 @@ pub fn main() {
                 },
                 _ => Some(s.to_string()),
             })
+            // FIXME: remove this line in 1.79 to only keep `--cfg clippy`.
             .chain(vec!["--cfg".into(), r#"feature="cargo-clippy""#.into()])
+            .chain(vec!["--cfg".into(), "clippy".into()])
             .collect::<Vec<String>>();
 
         // We enable Clippy if one of the following conditions is met