osdc/Objecter: mark all ops as known-if-redirected

This is 100% untested, but if we're going to mark redirected flags, we need to know if the lack of that flag is definitive. Add such a flag now, so that we can use redirect flags authoritatively in the future without requiring a new client.

(The kernel client will require a similar flag, but it doesn't have the redirect marker at all yet.)