Use better link for of subcontrib speakers
Use better link for of subcontrib speakers

We have no direct link to a subcontribution, so passing the subcontrib
id as the contrib id just results in an empty result list; linking to
the contrib is less confusing there.

pferreir/indico,DirkHoffmann/indico,DirkHoffmann/indico,pferreir/indico,indico/indico,ThiefMaster/indico,ThiefMaster/indico,indico/indico,indico/indico,pferreir/indico,ThiefMaster/indico,ThiefMaster/indico,DirkHoffmann/indico,pferreir/indico,indico/indico,DirkHoffmann/indico