SELinux: move SELINUX_MAGIC into magic.h

The selinuxfs superblock magic is used inside the IMA code, but is being
defined in two places and could someday get out of sync.  This patch moves the
declaration into magic.h so it is only done once.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index dec6dcb..31d677f 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -49,14 +49,12 @@
  * written in terms of .action, .func, .mask, .fsmagic, and .uid
  */
 static struct ima_measure_rule_entry default_rules[] = {
-	{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,
-	 .flags = IMA_FSMAGIC},
+	{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
-	{.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,
-	 .flags = IMA_FSMAGIC},
-	{.action = DONT_MEASURE,.fsmagic = 0xF97CFF8C,.flags = IMA_FSMAGIC},
+	{.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
+	{.action = DONT_MEASURE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
 	 .flags = IMA_FUNC | IMA_MASK},
 	{.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,