Do not use a user tag on apps, as it is ignored.

The build system does not honor user tags on apps,
and setting it is misleading.

This removes the confusion by making the makefiles
behave like they read.

Change-Id: Ia90c376d627c6c9faeccf040695b88bb32779f82
diff --git a/Android.mk b/Android.mk
index e3215e8..4c842c5 100755
--- a/Android.mk
+++ b/Android.mk
@@ -1,7 +1,7 @@
 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
-LOCAL_MODULE_TAGS := user
+LOCAL_MODULE_TAGS := optional
 
 LOCAL_SRC_FILES := $(call all-subdir-java-files)