Smack: Three symbols that should be static

The kbuild test robot reported a couple of these,
and the third showed up by inspection. Making the
symbols static is proper.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 11b752b..c20b154 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -139,7 +139,7 @@
 	struct smack_rule	*smk_rule;
 };
 
-LIST_HEAD(smack_rule_list);
+static LIST_HEAD(smack_rule_list);
 
 struct smack_parsed_rule {
 	struct smack_known	*smk_subject;