[Android-overlay] Fix Java imports.

Source/Android/src/org/dolphinemu/dolphinemu/settings/video/VideoSettingsFragment.java

@@ -6,6 +6,9 @@
 
 package org.dolphinemu.dolphinemu.settings.video;
 
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.content.DialogInterface;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
 import android.os.Bundle;