Fix dox build on windows

appveyor.yml

@@ -19,6 +19,7 @@ build_script:
   - mkdir .cargo
   - echo paths = ["."] > .cargo\config
   - git clone -q --depth 50 -b pending https://github.com/gtk-rs/examples _examples
+  - cargo doc --features "dox"
   - cd _examples
   - cargo build
   - cargo build --features gtk_3_18

src/unix_socket_address.rs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license, see the LICENSE file or <http://opensource.org/licenses/MIT>
 
 use std::ffi::OsStr;
+#[cfg(unix)]
 use std::os::unix::ffi::OsStrExt;
 use std::path;
 use std::ptr;