UBUNTU: SAUCE: Stacking v38: audit: multiple subject lsm values for netlabel

UBUNTU: SAUCE: Stacking v38: audit: multiple subject lsm values for netlabel

BugLink: https://bugs.launchpad.net/bugs/2012136
Refactor audit_log_task_context(), creating a new
audit_log_subject_context(). This is used in netlabel auditing
to provide multiple subject security contexts as necessary.

Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>