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

Thanks to Florian Weimer and Eric Sesterhenn for reporting, reviewing
and testing.
static void array_copy(json_t **dest, size_t dpos,
                       json_t **src, size_t spos,
                       size_t count)
{
    memcpy(&dest[dpos], &src[spos], count * sizeof(json_t *));
}

static void array_copy(json_t **dest, size_t dpos,
                       json_t **src, size_t spos,
                       size_t count)
{
    memcpy(&dest[dpos], &src[spos], count * sizeof(json_t *));
}
