[pkg-apparmor] Bug#879585: apparmor: Pin the AppArmor feature set in Stretch to Linux 4.9's

[intrigeri]

Control: severity -1 important

> It'll become more important once Linux 4.13+ lands in
> stretch-backports,

… which is now the case.

> but even then IMO that'll remain a normal severity bug because
> a combination of 2 non-default settings is required to trigger
> any problem.

Now that AppArmor is enabled by default in testing/sid, I suspect more
users of Stretch may want to try it out. So it would really be nice
to avoid breaking things for them in case they need a kernel from
backports, e.g. to support newer hardware.

Cheers,
-- 
intrigeri