This reverts commit 26a4001a98322ab903b8186b97f33c5b282828a5. It
breaks the NFS test:
http://hydra.nixos.org/build/13943148
Also, having more setuid programs is a bad thing security-wise.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.