loadable_icon_key helper functions

typedef struct  {
    GIcon *icon;
    int size;
} LoadableIconKey;

loadable_icon_key_new (GIcon *icon, int size)
{
    LoadableIconKey *key;

    key = g_slice_new (LoadableIconKey);
    key->icon = g_object_ref (icon);
    key->size = size;

    return key;
}

loadable_icon_key_hash (LoadableIconKey *key)
{
    return g_icon_hash (key->icon) ^ key->size;
}

loadable_icon_key_equal (const LoadableIconKey *a,
                         const LoadableIconKey *b)
{
    return a->size == b->size &&
        g_icon_equal (a->icon, b->icon);
}

static void
loadable_icon_key_free (LoadableIconKey *key)
{
    g_object_unref (key->icon);
    g_slice_free (LoadableIconKey, key);
}

static void destroy_cache_entry (MarlinIconInfo *icon_info)
{
    g_return_if_fail (icon_info != NULL);
    g_clear_object (&icon_info);
}