Attached is a more comprehensive patch set to add CUPS.

CUPS on non-MacOS systems depends on cups-filters, which in turn depends
on QPDF and IJS.

* QPDF is added by the first patch.

* IJS is part of ghostscript, but for some reason is not built even when
  passing "--with-ijs" as a configure flag.  There is no configure
  script and no usable Makefile in ./ijs, so we actually have to run
  ./autogen.sh after generating macros that work with libtool 2.4.2.
  The second patch adds a new very ugly phase that does just that.  I'd
  love to change this if someone can come up with a better way to do
  this.

* cups-filters also depends on CUPS libraries and binaries, so
  cups-minimal has been added to satisfy this dependency.  During
  installation, cups-filters attempts to install files to the CUPS
  package output directory.  The install phase is modified to direct the
  files to the output directory of cups-filters.

* the CUPS package itself then adds links to the required files in
  cups-filters.  CUPS does not come with a mechanism to load filters,
  backends, charsets, mime files, etc from alternative directories, so I
  chose to use symlinks.

* the CUPS tests are run before the installation of any symlinks, so to
  establish a working test environment quite a lot of fixes to the test
  phase are needed.  Without the files from cups-filters seven tests
  fail.  With the files in place only three tests fail.  I have not been
  able to fix these remaining failures, even though I have been trying
  for a long time.

I have addressed your previous comments about outputs and the CUPS
license (gpl2 instead of gpl2+).

Thanks in advance for your review!

-- Ricardo