Apply cargo fix --edition-idioms fixes

Author: LunaBorowska

tests/compile-test.rs

@@ -9,7 +9,7 @@
 
 #![feature(test)]
 
-extern crate compiletest_rs as compiletest;
+use compiletest_rs as compiletest;
 extern crate test;
 
 use std::env::{set_var, var};

tests/matches.rs

@@ -9,7 +9,7 @@
 
 #![feature(rustc_private)]
 
-extern crate clippy_lints;
+use clippy_lints;
 extern crate syntax;
 use std::collections::Bound;
 

tests/needless_continue_helpers.rs

@@ -10,7 +10,7 @@
 // Tests for the various helper functions used by the needless_continue
 // lint that don't belong in utils.
 
-extern crate clippy_lints;
+
 use clippy_lints::needless_continue::{erode_block, erode_from_back, erode_from_front};
 
 #[test]

tests/versioncheck.rs

@@ -7,8 +7,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern crate cargo_metadata;
-extern crate semver;
+use cargo_metadata;
+
 use semver::VersionReq;
 
 #[test]