Re: [PATCH 06/13] oidset: introduce `oidset_equal()`

Patrick Steinhardt [off-list ref] writes:

Introduce a new function that allows the caller to verify whether two
oidsets contain the exact same object IDs.

Note that this change requires us to change `oidset_iter_init()` to
accept a `const struct oidset`.

Iterator shouldn't mutate the set it is iterating over, so
that sounds good.