selinux: clean up selinux_enabled/disabled/enforcing_boot

Rename selinux_enabled to selinux_enabled_boot to make it clear that
it only reflects whether SELinux was enabled at boot.  Replace the
references to it in the MAC_STATUS audit log in sel_write_enforce()
with hardcoded "1" values because this code is only reachable if SELinux
is enabled and does not change its value, and update the corresponding
MAC_STATUS audit log in sel_write_disable().  Stop clearing
selinux_enabled in selinux_disable() since it is not used outside of
initialization code that runs before selinux_disable() can be reached.
Mark both selinux_enabled_boot and selinux_enforcing_boot as __initdata
since they are only used in initialization code.

Wrap the disabled field in the struct selinux_state with
CONFIG_SECURITY_SELINUX_DISABLE since it is only used for
runtime disable.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/ibpkey.c

@@ -222,7 +222,7 @@ static __init int sel_ib_pkey_init(void)
 {
 	int iter;
 
-	if (!selinux_enabled)
+	if (!selinux_enabled_boot)
 		return 0;
 
 	for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {