[pkg-apparmor] Bug#881936: apparmor: support usrmerge

[intrigeri]

Control: retitle -1 the upstream test suite does not support usrmerge

intrigeri:
> Can you please send this upstream as a merge request there:

>   https://gitlab.com/apparmor/apparmor/

> ?

> If you prefer not to, I can forward. But IIRC it's not your first
> contribution so on the long term, it would make sense if you would
> send your proposed changes directly upstream :)

Ping?