Change some instances of .connect() to .join()

src/librustc_driver/lib.rs

@@ -606,7 +606,7 @@ Available lint options:
         for (name, to) in lints {
             let name = name.to_lowercase().replace("_", "-");
             let desc = to.into_iter().map(|x| x.as_str().replace("_", "-"))
-                         .collect::<Vec<String>>().connect(", ");
+                         .collect::<Vec<String>>().join(", ");
             println!("    {}  {}",
                      padded(&name[..]), desc);
         }