Add the following trait impls: - `impl Extend<OsString> for OsString` - `impl<'a> Extend<&'a OsStr> for OsString` - `impl FromIterator<OsString> for OsString` - `impl<'a> FromIterator<&'a OsStr> for OsString` Because `OsString` is a platform string with no particular semantics, concatenating them together seems acceptable.