Possibly because of different behavior on the newly update
cloud-image, trying to run 'apt-get build-dep' results in:

   E: You must put some 'source' URIs in your sources.list

This enables all source repos (even though some are not
needed) for simplicity sake.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190613130718.3763-5-crosa@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>