Run print tests at build time and as autopkgtests

@duck I'm submitting this merge request as part of work to include libdisplay-info by default in Ubuntu Desktop. mutter/experimental has a runtime dependency on libdisplay-info.

Although it's not possible to easily run the full upstream testsuite since as you noticed it depends on a particular commit of edid-decode, I noticed that at least the "print" tests pass. Therefore, this merge request enables running those tests with dh_auto_test.

To ensure that these tests continue to pass when a new version of edid-decode is uploaded, I added a simple autopkgtest to rerun the build. By using Restrictions: build-needed, I avoided a more verbose dh_auto_configure && dh_auto_build && dh_auto_test autopkgtest or figuring out how to build di-edid-print.c manually and run the available tests.