Some incorrect setups might have multiple audiences
where they are trying to use a single authentication
endpoint for multiple services.
Nevertheless OpenID spec allows it to make it
even more confusin for no good reason.
> It MUST contain the OAuth 2.0 client_id of the
> Relying Party as an audience value. It MAY also
> contain identifiers for other audiences. In the
> general case, the aud value is an array of case
> sensitive strings. In the common special case
> when there is one audience, the aud value MAY
> be a single case sensitive string.
fixes#12809
3735450e7e