FlaggedApi: enable enforcement for all non-updatable APIs

(cherry pick of 7da1d25541124cf0c6ced6eb0af738fb9263b77a
 and 38dd161e4f88b43e7d251f8888714d79c2557b7f)

Bug: 297362755
Test: make checkapi
Merged-In: If7333ead86d9028ab0a1cc8f25fc534cb13a1858
Merged-In: I4d384efac8a8d3b183d9b207b195ad5489db9e55
Change-Id: I4d384efac8a8d3b183d9b207b195ad5489db9e55
diff --git a/Android.bp b/Android.bp
index ccff26f..07d703d 100644
--- a/Android.bp
+++ b/Android.bp
@@ -568,6 +568,7 @@
     "--api-lint-ignore-prefix org. " +
     "--error NoSettingsProvider " +
     "--error UnhiddenSystemApi " +
+    "--error UnflaggedApi " +
     "--force-convert-to-warning-nullability-annotations +*:-android.*:+android.icu.*:-dalvik.* " +
     "--hide BroadcastBehavior " +
     "--hide CallbackInterface " +