to run the varnishd worker process as a different user than the VCC
and CC subprocesses.

It is mandatory that the workuser has the same login group as the user
subparamter.

Recommended values for packaging:

	-junix,user=varnish	"varnish" user has login group "varnish"
	-junix,workuser=vrun	"vrun" user has login group "varnish"