This reverts commit 79956621.

Before we can merge something like this we need to have it be behind a
configure flag and quite probably be an opt-in feature (--enable-pam).

This should fix Jenkins, PPA builds and the current binary conflicts
between the lxcfs and lxc package builds (snap and archive).
Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>