keys: explicitly include required slab.h header file.

Since these two source files invoke kmalloc(), they should explicitly
include <linux/slab.h>.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index c615d473..bd237b0 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -15,6 +15,7 @@
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <linux/seq_file.h>
+#include <linux/slab.h>
 #include <asm/uaccess.h>
 #include "internal.h"