[Samba] enable-cups in spec file

[David Schlenk]

It appears that --enable-cups made it into the Redhat srpm. Neat.

I've been adding that one line to it forever, and did it again this 
time without checking for its presence, thus causing the compile to 
fail. Thought I'd let the world know in case someone else did something 
equally foolish and got confused with config.sub errored out.
--
David Schlenk
Operating Systems Analyst
Bethel University
Saint Paul, Minnesota
david-schlenk at bethel.edu