audit: check audit_enabled in audit_tree_log_remove_rule()

Respect the audit_enabled flag when printing tree rule config change
records.

See: https://github.com/linux-audit/audit-kernel/issues/50

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: tweak the subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>

kernel/audit_tree.c

@@ -497,6 +497,8 @@ static void audit_tree_log_remove_rule(struct audit_krule *rule)
 {
 	struct audit_buffer *ab;
 
+	if (!audit_enabled)
+		return;
 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 	if (unlikely(!ab))
 		return;