Method to override buildlink inclusion

[Martijn van Buul <pino%dohd.org@localhost>]

Hi,

For a few software packages, there are several versions in pkgsrc - especially
if you include wip into consideration. For example, there's lang/clisp,
wip/clisp and wip/clisp-current, and they're all different. Likewise for
lang/mono and wip/mono. Is there a clean way to inform pkgsrc that I do
*not* want lang/mono (since it won't even compile), but that it should use
wip/mono instead? 

I'm even prepared to do this on a per-package basis. Right now, I have to
modify the package makefile and change the included buildlink, and I can't
help but wonder if there isn't a more elegant solution. 

-- 
Martijn van Buul - pino%dohd.org@localhost