Expose accept_filter parameter to Linux
Expose accept_filter parameter to Linux

Disabled by default. Prompted by Rafael Zalamena
(rafaelfz at taghos dot com dot br) on varnish-dev.

franciscovg/Varnish-Cache,feld/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache,franciscovg/Varnish-Cache,feld/Varnish-Cache,franciscovg/Varnish-Cache,varnish/Varnish-Cache,gquintard/Varnish-Cache,franciscovg/Varnish-Cache,gquintard/Varnish-Cache,varnish/Varnish-Cache,franciscovg/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache