Basic Testing of the Gutenprint drivers for CUPS

The gutenprint-testing package does
basic testing of the Gutenprint drivers
during build-time of gutenprint-testing.

The tests are re-done automatically whenever
a build requirement of gutenprint-testing changes
via the automated package rebuilds in OBS.
Explicit build requirements of gutenprint-testing
are gutenprint plus cups and cups-filters
(i.e. what constitutes the base printing system).

It tests the Gutenprint printer drivers for CUPS
by running the drivers via the cupsfilter program.
See /usr/share/doc/packages/gutenprint-testing/README.SUSE
and cf. the section "How to test a printer driver package" in
https://en.opensuse.org/openSUSE:How_to_contribute_to_the_Printing_project