Add obfs4proxy to the default tor apparmor profile

The current apparmor profile shipped with tor allows tor to launch obfsproxy but not Yawning's new obfs4proxy. To fix you just need to add:

  /usr/bin/obfs4proxy PUx,

to debian/tor.apparmor-profile.abstraction. I specify that path because that's where the current debian package installs to; however, obfs4's debian packaging source does not appear to be included in tor's git. Perhaps Yawning can verify whether this will continue to be the stable install location?

Trac:
Username: vladtsyrklevich