The API to end auditing has historically been for auditd to set the
pid to 0. This patch restores that functionality.

See: https://github.com/linux-audit/audit-kernel/issues/69Reviewed-by: NRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: NSteve Grubb <sgrubb@redhat.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>