Enable "show language switch key" settings on K and before

"Show language switch key" and "Switch to other IME" settings are
enabled on KitKat and before. On L and later, its preference settings
UI gets hide and the settings values are forcibly set to true.

Bug: 14854377
Change-Id: I10456408452280a1b7688fd1f168933937666c9f
diff --git a/java/res/xml/prefs.xml b/java/res/xml/prefs.xml
index 61ebb69..a629862 100644
--- a/java/res/xml/prefs.xml
+++ b/java/res/xml/prefs.xml
@@ -153,6 +153,7 @@
                 android:defaultValue="true" />
             <CheckBoxPreference
                 android:key="pref_include_other_imes_in_language_switch_list"
+                android:dependency="pref_show_language_switch_key"
                 android:title="@string/include_other_imes_in_language_switch_list"
                 android:summary="@string/include_other_imes_in_language_switch_list_summary"
                 android:persistent="true"