Upgrade rust/crates/pin-project to 0.4.23

* Keep local change in src/lib.rs:
  // ANDROID: Use std to allow building as a dylib.

Test: make
Change-Id: I5d5a43c5ad9e42c7ecaeb163bc9a25da2ab233a4
diff --git a/examples/enum-default-expanded.rs b/examples/enum-default-expanded.rs
index 3e7cb3c..cea3ae5 100644
--- a/examples/enum-default-expanded.rs
+++ b/examples/enum-default-expanded.rs
@@ -84,7 +84,10 @@
     // See ./struct-default-expanded.rs and https://github.com/taiki-e/pin-project/pull/53.
     // for details.
     struct __Enum<'pin, T, U> {
-        __pin_project_use_generics: ::pin_project::__private::AlwaysUnpin<'pin, (T, U)>,
+        __pin_project_use_generics: ::pin_project::__private::AlwaysUnpin<
+            'pin,
+            (::pin_project::__private::PhantomData<T>, ::pin_project::__private::PhantomData<U>),
+        >,
         __field0: T,
     }
     impl<'pin, T, U> ::pin_project::__private::Unpin for Enum<T, U> where