man/lintian.pod.in: Remove --packages-file reference

Lintian no longer supports --packages-file (replaced by
--packages-from-file).

Signed-off-by: Niels Thykier <niels@thykier.net>
lintian: Remove call to undefined function

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