CVE-2013-6401: Change hash function, randomize hashes

Thanks to Florian Weimer and Eric Sesterhenn for reporting, reviewing
and testing.
size_t json_array_size(const json_t *json)
{
    if(!json_is_array(json))
        return 0;

    return json_to_array(json)->entries;
}

size_t json_array_size(const json_t *json)
{
    if(!json_is_array(json))
        return 0;

    return json_to_array(json)->entries;
}
