selinux-autorelabel: Increment boot_indeterminate grub environment variable
    
    For the new grub auto-hide feature:
    https://fedoraproject.org/wiki/Changes/HiddenGrubMenu
    
    Grub needs to know if the previous boot succeeded. This is tracked
    through flags in the grub environment.
    
    A selinux autorelabel is special, because it reboots the machine without
    completing the boot in the normal manner.
    
    grub checks the (new) boot_indeterminate grub environment variable to deal
    with this. This is a variable containing a count of special boots since
    the last successful normal boot. If this variable is 1 then it also treats
    the previous boot as successful. The idea is that an autorelabel (or
    offline updates) increments boot_indeterminate, so normally after a reboot
    it will be 1 and the grub menu stays hidden. But if we end up in a selinux
    autorelabel loop for some reason, then it will be bigger then 1 (*) and
    the grub menu will be shown allowing the user to try and fix things.
    
    *) grub itself will also increment it if it is 1 so that even if it gets
    incremented only once, that still only makes 1 boot count as successful.
    
    This commit makes the selinux-autorelabel script call:
    grub2-editenv - incr boot_indeterminate
    for proper integration with this new grub feature.
    
    Signed-off-by: Hans de Goede <hdegoede@redhat.com>