Add monostate to optional safe unions.

Bug: 116156870
Test: hidl_test, hidl_test_java
Change-Id: Ie17a80dee982775e267a39086016071ac2361fb5
diff --git a/radio/1.3/Android.bp b/radio/1.3/Android.bp
index 6a9b1d0..b6610e0 100644
--- a/radio/1.3/Android.bp
+++ b/radio/1.3/Android.bp
@@ -17,6 +17,7 @@
         "android.hardware.radio@1.1",
         "android.hardware.radio@1.2",
         "android.hidl.base@1.0",
+        "android.hidl.safe_union@1.0",
     ],
     types: [
         "AccessNetwork",