Add VGEM to the Linux image that runs in the CI. There are tests that we
plan to add in the future that need this.
This brings a complication, as we already have VKMS in the image. The
order in which DRM devices are loaded is not always the same, so the
node they receive is non-deterministic. Until now we were sure that VKMS
(the virtual device we use to run the DRM-backend tests in the CI) would
be in "/dev/dri/card0", but now we can't be sure. To deal with this
problem we find the node of each device using a one-liner shell script.
This commit also updates the documentation section that describes
specificities of DRM-backend tests in our test suite.
Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Leandro Ribeiro
08dbd29e33