Make packagemanager_aidl available to Virt APEX

Even though the interface is unstable, it's okay to be used by the Virt
APEX since the apex itself is unstable(and not-updatable) as well. We
need to stabilize the interface when making the apex updatable.

Bug: 199146189
Test: m
Change-Id: Idd98e3d1876b83a357f50ac8892ecdde871a616c
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 8e0ac17..c748277 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -306,6 +306,14 @@
         "aidl/android/content/pm/ApexStagedEvent.aidl",
         "aidl/android/content/pm/StagedApexInfo.aidl",
     ],
+    backend: {
+        rust: {
+            apex_available: [
+                "com.android.virt",
+            ],
+            enabled: true,
+        },
+    },
 }
 
 aidl_interface {