Log Message:
print/ghostscript-agpl: Add default-off cups option

This is basically a port of the cups option code from
../ghostscript-gpl.  Since the last GPL3 gs release, some programs
have migrated to the cups-filters package.  Thus, they are no longer
installed by cups, and the option is much simpler.

I verified that the cups driver appears in "gs -h", but have not
tested it.

While the option defaults to off, I bumped PKGREVISION anyway.