libselinux: normalize enforce values from the kernel

Normalize enforce values received from the kernel via
/sys/fs/selinux/enforce or netlink selinux notifications
to ensure that we always return a 0 or 1 to userspace code.
selinux_status_getenforce(), which reads the enforce value
via the SELinux kernel status page (/sys/fs/selinux/status)
already normalizes its result, so we do not need to update it.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
2 files changed