Use --copy-out to generate .bp file.

* The original include command now works without
  local patch or post_update.sh.
* Add missing std.diff

Bug: 171659849
Test: make
Test: tools/external_updater/updater.sh update --refresh --keep-date rust/crates/proc-macro-nested
Change-Id: Ifcacf844017ef1332f1abad6e8d47c99dfea873a
diff --git a/src/lib.rs b/src/lib.rs
index a8b7694..9ec6df0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -43,7 +43,7 @@
 // ANDROID: Use std to allow building as a dylib.
 extern crate std;
 
-include!("../out/count.rs");  // ANDROID
+include!(concat!(env!("OUT_DIR"), "/count.rs"));
 
 #[doc(hidden)]
 #[macro_export]