Add RPC binder as unstable API with Rust bindgen

The build targets have limited visibility to the current (and hopefully
no more) clients.

Bug: 190547489
Bug: 189947807
Test: use in the client

Change-Id: I8701066e0b44c21d2b2a77bbf872efd4e28c3662
diff --git a/libs/binder/rust/Android.bp b/libs/binder/rust/Android.bp
index 7d655d8..8d27eed 100644
--- a/libs/binder/rust/Android.bp
+++ b/libs/binder/rust/Android.bp
@@ -106,6 +106,21 @@
     ],
 }
 
+// TODO(b/184872979): remove once the Rust API is created.
+rust_bindgen {
+    name: "libbinder_rpc_unstable_bindgen",
+    wrapper_src: "src/binder_rpc_unstable.hpp",
+    crate_name: "binder_rpc_unstable_bindgen",
+    source_stem: "bindings",
+    shared_libs: [
+        "libutils",
+    ],
+    apex_available: [
+        "com.android.compos",
+        "com.android.virt",
+    ],
+}
+
 rust_test {
     name: "libbinder_rs-internal_test",
     crate_name: "binder",