Calendar now segfaults due to faling function
gtk_style_context_remove_provider_for_screen in application finalize method.
As application finalize method is called only when the application closes,
there isn't any hard requirement to cleanup every trailings. Operating
System shall take care of that.
So removing the failing functions so as to not segfault on exit anymore.
https://bugzilla.gnome.org/show_bug.cgi?id=773871