Attr for debian

Hi, an old config change in commit 0fa76242 is hereby suggested to be reverted.

The tests are good these days and I've not really seen a rawback to have libattr these days (you don't need to use selinux, but get the dac labels afaics in a quick check). And you are affected by this bug to restore image ownership as well.

So I wonder if we'd want to turn that on in Debian as well?

Note: targeted at experimental as there the latest (6.4) changes are residing.

P.S. while looking at d/rules today I couldn't resist trying to fix whitespaces, feel free to ignore that commit if you don't agree (or if review takes a while as these changes naturally bit-rot fast and might no more auto-apply).