Upgrade AndroidFrameworkUid to be fatal error.

We've fixed the one remaining example of code that accidentally
crosses UID with userId, so this change upgrades the check to become
a fatal build error to prevent future bugs.

Bug: 155703208
Test: atest error_prone_android_framework_test
Change-Id: I3bc46f8039a88b5f3d5f89dc9b5fda785d5c654f
diff --git a/Android.bp b/Android.bp
index f69f9d8..4121b8a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -601,6 +601,7 @@
     errorprone: {
         javacflags: [
             "-Xep:AndroidFrameworkCompatChange:ERROR",
+            "-Xep:AndroidFrameworkUid:ERROR",
         ],
     },
 }