Audit: increase the maximum length of the key field

Key lengths were arbitrarily limited to 32 characters.  If userspace is going
to start using the single kernel key field as multiple virtual key fields
(example key=key1,key2,key3,key4) we should give them enough room to work.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/audit.h

@@ -146,7 +146,7 @@
 /* Rule structure sizes -- if these change, different AUDIT_ADD and
  * AUDIT_LIST commands must be implemented. */
 #define AUDIT_MAX_FIELDS   64
-#define AUDIT_MAX_KEY_LEN  32
+#define AUDIT_MAX_KEY_LEN  256
 #define AUDIT_BITMASK_SIZE 64
 #define AUDIT_WORD(nr) ((__u32)((nr)/32))
 #define AUDIT_BIT(nr)  (1 << ((nr) - AUDIT_WORD(nr)*32))