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 --cc security/keys/request_key.c
Simple merge

diff --cc security/keys/request_key_auth.c
Simple merge