Required packetizers are no longer loading (and any other overrideable module through module_need_var)

regression by 2480a515

static inline module_t *module_need_var(vlc_object_t *obj, const char *cap,
                                        const char *varname)
{
    char *list = var_InheritString(obj, varname);
    if (unlikely(list == NULL))
        return NULL;

    module_t *m = module_need(obj, cap, list, false);

    free(list);
    return m;
}