[J3] Private enumerators

[Van Snyder]

Gary objected to private enumerators.

Access specs control access to identifiers, not objects.

He didn't like the possibility that one might be able to get the value
of an enumerator for which the module did not publish the name, using,
for example, INT(foo)+1 or foo%next().

I'm not quite sure how having a public enumerator makes that better.  In
fact, having a public enumerator seems to make it worse.

Can we have a mail vote to proceed with 19-249r1?