Add bash, setup and selinux-policy to critical-path-base
    
    bash, obviously, affects console login as our default shell. So
    does setup, because the macros from it are sourced when any
    shell starts; them being badly broken could prevent shells
    working at all. And selinux-policy, of course, can stop just
    about *anything* working...
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>