testset: Fix expected output

Signed-off-by: Niels Thykier <niels@thykier.net>
Add generic infrastructure for checking common-licenses

Add data/copyright-file/common-licenses in order to robustly check
reference to /usr/share/common-licenses.

Signed-off-by: Niels Thykier <niels@thykier.net>
Warn about apache-2 license and no link to common license

Warn if license is apache-2 and we do not link to
/usr/share/license-common

Signed-off-by: Niels Thykier <niels@thykier.net>