Update tests to current rustc

clippy_lints/src/lib.rs

@@ -1,7 +1,6 @@
 // error-pattern:cargo-clippy
 
 #![feature(box_syntax)]
-#![feature(alloc)]
 #![feature(custom_attribute)]
 #![feature(i128_type)]
 #![feature(i128)]

rls.toml

@@ -1 +1 @@
-build_lib = true
+workspace_mode=true

tests/ui/useless_attribute.rs

@@ -2,7 +2,7 @@
 #![plugin(clippy)]
 #![warn(useless_attribute)]
 
-#[allow(dead_code)]
+#[allow(dead_code, unused_extern_crates)]
 extern crate clippy_lints;
 
 // don't lint on unused_import for `use` items

tests/ui/useless_attribute.stderr

@@ -1,8 +1,8 @@
 error: useless lint attribute
  --> $DIR/useless_attribute.rs:5:1
   |
-5 | #[allow(dead_code)]
-  | ^^^^^^^^^^^^^^^^^^^ help: if you just forgot a `!`, use: `#![allow(dead_code)]`
+5 | #[allow(dead_code, unused_extern_crates)]
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: if you just forgot a `!`, use: `#![allow(dead_code, unused_extern_crates)]`
   |
   = note: `-D useless-attribute` implied by `-D warnings`