Bug#760526: Enable AppArmor support (using libapparmor)

[Michael scherer]

So, investigating the problem.

The issue is that :

 ReadOnlyDirectories = /

make aa_change_onexec fail with 

 Oct 11 23:22:25 test-debian systemd[1985]: Failed at step APPARMOR spawning /usr/bin/tor: Read-only file system

( once there is proper reporting ). I suspect the issue is upstream, with the ordering of readonly vs apparmor.

Adding :

 ReadWriteDirectories = /proc

Seems to fix the issue as well. I am trying to see if I can fix properly upstream by moving around 
apparmor support in the source code.