Fix bare-outfile test

Author: Kobzol

tests/run-make/bare-outfile/rmake.rs

@@ -3,13 +3,9 @@
 
 //@ ignore-cross-compile
 
-use run_make_support::{run, rustc, tmp_dir};
-use std::env;
-use std::fs;
+use run_make_support::{run, rustc};
 
 fn main() {
-    fs::copy("foo.rs", tmp_dir().join("foo.rs")).unwrap();
-    env::set_current_dir(tmp_dir());
     rustc().output("foo").input("foo.rs").run();
     run("foo");
 }