fs: make available to wasm under tokio_unstable (#6822)

tokio/src/fs/open_options.rs

@@ -394,6 +394,7 @@ impl OpenOptions {
     }
 
     /// Returns a mutable reference to the underlying `std::fs::OpenOptions`
+    #[cfg(any(windows, unix))]
     pub(super) fn as_inner_mut(&mut self) -> &mut StdOpenOptions {
         &mut self.0
     }

tokio/src/macros/cfg.rs

@@ -97,7 +97,6 @@ macro_rules! cfg_fs {
     ($($item:item)*) => {
         $(
             #[cfg(feature = "fs")]
-            #[cfg(not(target_os = "wasi"))]
             #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
             $item
         )*