Fix vtest on SmartOS
Fix vtest on SmartOS

It looks like it was simply a difference between automake versions,
let's see if it pans out.

Refs #2139

feld/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache