Make flags UI available on release build of launcher

The UI will only be shown on eng/userdebug platform builds.

Bug: 117223984
Change-Id: I27843f2d856a4a19f3fe53c4d306606eaa5714a2
diff --git a/res/xml/flag_preferences.xml b/res/xml/flag_preferences.xml
new file mode 100644
index 0000000..aea1a6a
--- /dev/null
+++ b/res/xml/flag_preferences.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+-->
+
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
+    android:key="feature_flags"
+    android:persistent="false">
+
+</PreferenceScreen>
\ No newline at end of file