adduser: Fix confusion between `uclass` and `_class`.

[des]

Summary

This caused adduser to produce an invalid pw(8) command line. Due to
bugs in pw(8), the command line was silently accepted and led to the
user being created, but locked out and with no home directory.

Fixes: 170d0882903e
MFC after: 3 days

[des]

move _another_user

[• karels]

I may not be the best reviewer for this change; I haven't used "local".

[• karels]

I applied this change (only) and ran the script; I got:

OK? (yes/no) [yes]:
adduser.fix: INFO: Successfully added (mike) to the user database.
local: Not in a function
Add another user? (yes/no) []:

[des]

In D45098#1028400, @karels wrote:

I may not be the best reviewer for this change; I haven't used "local".

Perhaps, but you reported the bug and you can at least test the patch.

[des]

not in a function

[• karels]

This version works (adds the user correctly and defaults to not adding another user). Tested only on UFS; will test on ZFS in an hour or so.

[• karels]

Works on ZFS too; dataset added and home directory set up correctly.

[des]

Can you please approve it, then?

[• karels]

Accepted, based mostly on Alan's previous approval.