am 8840fa7f: Split system_app from system.

* commit '8840fa7f':
  Split system_app from system.

system.te

-type system_app, domain;
-permissive system_app;
-app_domain(system_app)
-unconfined_domain(system_app)
-
+#
+# System Server aka system_server spawned by zygote.
+# Most of the framework services run in this process.
+#
 type system, domain;
 permissive system;
 unconfined_domain(system);

system_app.te

+#
+# Apps that run with the system UID, e.g. com.android.system.ui,
+# com.android.settings.  These are not as privileged as the system
+# server.
+#
+type system_app, domain;
+permissive system_app;
+app_domain(system_app)
+unconfined_domain(system_app)