rust: Visibility exports for bindgen

We are now default restricting bindgen visibility to subpackages. This
change is part of a set of changes adding explicit visibility for
bindgen libraries which are already being used elsewhere.

* If these visibility rules are to allow access by the safe bindings
  library which lives elsewhere in the codebase, no action is needed.
* If safe bindings do not exist, and you own this library, now is a good
  time to think about producing them and transitioning your (now
  enumerated) client list.
* If safe bindings exist, but there is a surprise client of the raw
  bindings on this list, now is a good time to talk to them about why
  they don't want to use your safe bindings.

Bug: 166332519
Test: m
Change-Id: I64941daa2a61b6342a3281906a6a1baf983d02c8
diff --git a/Android.bp b/Android.bp
index 1a8fbf9..196b4aa 100644
--- a/Android.bp
+++ b/Android.bp
@@ -163,6 +163,7 @@
 rust_bindgen {
     name: "libopen_dice_cbor_bindgen",
     defaults: ["libopen_dice.rust_defaults"],
+    visibility: ["//system/security/diced/open_dice_cbor"],
     wrapper_src: "rust/dice.h",
     crate_name: "open_dice_cbor_bindgen",
     source_stem: "bindings",
@@ -203,6 +204,7 @@
 rust_bindgen {
     name: "libopen_dice_bcc_bindgen",
     defaults: ["libopen_dice.rust_defaults"],
+    visibility: ["//system/security/diced/open_dice_cbor"],
     wrapper_src: "rust/android/bcc.h",
     crate_name: "open_dice_bcc_bindgen",
     source_stem: "bindings",