fails badly if fakeroot is not available

[boyska]

If $UID != 0, fakeroot is used for check-virt.
That's correct, but should be done only if fakeroot is available, otherwise it's worse than not having that lines at all. At the moment I am workarounding this adding fakeroot as a recommends, but it is not the proper solution.

I think that if fakeroot is not available, and we are not root, we should just conclude that we are not in a virtual environment (not giving any warning therefore).