UBUNTU: SAUCE: LSM: Verify LSM display sanity in binder

UBUNTU: SAUCE: LSM: Verify LSM display sanity in binder

Verify that the tasks on the ends of a binder transaction
use the same "display" security module. This prevents confusion
of security "contexts".

Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>