message: no RwLock on Windows
diff: @@ -8,8 +8,12 @@ fn main() {
  let _ = m.lock();
  drop(m);
  + // We don't provide RwLock on Windows
  + #[cfg(not(target_os = "windows"))]
  + {
  let rw = sync::RwLock::new(0);
  let _ = rw.read();
  let _ = rw.write();
  drop(rw);
  }
  +}
  