configure.ac: Get the needed libs from cups-config (for OpenBSD)

[Alexandre Julliard]

André Hentschel <nerv at dawncrow.de> writes:

> Inspired by Matias Colli, see bug 17896.
> I made sure it doesn't hurt on other OS and send it because it doesn't seem he will do it and it's a oneliner.

It doesn't work for me on Debian testing, not without manually creating
symlinks for the libs that cups-config requires. It sounds like OpenBSD
should fix their libcups build.

-- 
Alexandre Julliard
julliard at winehq.org