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/patches/std.diff b/patches/std.diff
new file mode 100644
index 0000000..6d71af2
--- /dev/null
+++ b/patches/std.diff
@@ -0,0 +1,14 @@
+diff --git a/src/lib.rs b/src/lib.rs
+index 9ec6df0..0cd8302 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -40,6 +40,9 @@
+ 
+ #![no_std]
+ 
++// ANDROID: Use std to allow building as a dylib.
++extern crate std;
++
+ include!(concat!(env!("OUT_DIR"), "/count.rs"));
+ 
+ #[doc(hidden)]