Add Wi-Fi Calling preference screen

Change-Id: Ie89902b55c5c4184236636f5039b3246a9c0bda5
diff --git a/src/com/android/settings/Settings.java b/src/com/android/settings/Settings.java
index 84bf6157..ebb7491 100644
--- a/src/com/android/settings/Settings.java
+++ b/src/com/android/settings/Settings.java
@@ -101,5 +101,6 @@
 
     public static class TopLevelSettings extends SettingsActivity { /* empty */ }
     public static class ApnSettingsActivity extends SettingsActivity { /* empty */ }
+    public static class WifiCallingSettingsActivity extends SettingsActivity { /* empty */ }
 }