Name for new itertools object to make iterators thread-safe

[pitrou (Antoine Pitrou)]

@eendebakpt

In the free-threading build several iterators are not thread safe under concurrent iteration. Work is in progress to prevent concurrent iteration to corrupt the interpreter state, but it is acceptable for an iterator to return “funny” results.

Is it acceptable, really? Would it be that costly to ensure that all built-in iterators are thread-safe by default?