remove unused imports

Author: mustartt

compiler/rustc_metadata/src/creader.rs

@@ -1,7 +1,6 @@
 //! Validates all used crates and extern libraries and loads their metadata
 
 use std::error::Error;
-use std::ffi::OsString;
 use std::ops::Fn;
 use std::path::Path;
 use std::str::FromStr;