Print system APIs require a permission

Test: Checked that enabling and disabling a print service is still
      observed by the Settings app
Bug: 62350107
Change-Id: I12ed72767127c2ee2a9266140807ed1bd55800c3
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index c73c909..8421422 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -84,6 +84,7 @@
     <uses-permission android:name="android.permission.DELETE_PACKAGES"/>
     <uses-permission android:name="android.permission.MANAGE_APP_OPS_RESTRICTIONS"/>
     <uses-permission android:name="android.permission.HIDE_NON_SYSTEM_OVERLAY_WINDOWS"/>
+    <uses-permission android:name="android.permission.READ_PRINT_SERVICES" />
 
     <application android:label="@string/settings_label"
             android:icon="@drawable/ic_launcher_settings"