fix some errors

Author: sylvestre

tests/by-util/test_whoami.rs

@@ -4,7 +4,9 @@
 // file that was distributed with this source code.
 
 use uu_tests_common::new_ucmd;
+#[cfg(unix)]
 use uu_tests_common::unwrap_or_return;
+#[cfg(unix)]
 use uu_tests_common::util::expected_result;
 #[cfg(unix)]
 use uu_tests_common::util::{is_ci, whoami, TestScenario};