er...Adam, thats a feature, not a bug. ;) See the MacPorts FAQ via www.macports.org
But that FAQ entry needs updating, and perhaps the policy itself needs review ..... In any event, it was felt that MacPorts was doing a better job keeping the libs up-to-date. I say this for information only. If you want to discuss this you find competent folks on the macport-dev mailing list.
Well that's not the case as the macports version of render-proto is out of date and causes xserver to not compile when it is used.
Why not have it be a lib dependency like you do for libX11? lib:libX11.6:xorg
so port:fontconfig would become: lib:libfontconfig.1:fontconfig