unimplemented encode/decode implementations for wasm

The cfg() guards around the encode/decode implementations result in the
crate being unusable on wasm32-unknown-unknown.

These lines don't implement the functionality for that platform (there
is file system equivalent there), which makes the crate usable again for
file system unrelated tasks like encoding using the "cbor" crate.

Author: chrysn

src/serialize.rs

@@ -1371,6 +1371,10 @@ impl Encodable for path::Path {
         let v = self.as_os_str().encode_wide().collect::<Vec<_>>();
         v.encode(e)
     }
+    #[cfg(target_arch = "wasm32")]
+    fn encode<S: Encoder>(&self, _e: &mut S) -> Result<(), S::Error> {
+        unimplemented!();
+    }
 }
 
 impl Encodable for path::PathBuf {
@@ -1406,6 +1410,10 @@ impl Decodable for path::PathBuf {
         p.push(s);
         Ok(p)
     }
+    #[cfg(target_arch = "wasm32")]
+    fn decode<D: Decoder>(_d: &mut D) -> Result<path::PathBuf, D::Error> {
+        unimplemented!();
+    }
 }
 
 impl<T: Encodable + Copy> Encodable for Cell<T> {