Gio.ListStore overrides: use splice() when adding/removing many items with newer GLib. See #115
g_list_store_splice() was broken when adding items and fixed with glib 2.57.1. See https://bugzilla.gnome.org/show_bug.cgi?id=795307
This makes the override code use the fast splice method with newer glib and uses a slower fallback version with broken glib versions.