Some seccomp flags will become exclusive, so the selftest needs to
be adjusted to mask those out and test them individually for the "all
flags" tests.

Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Tycho Andersen <tycho@tycho.ws>
Acked-by: James Morris <jamorris@linux.microsoft.com>