[tz] Changing 24:00 to 0:00 where possible

[Paul Gilmartin]

On 4/4/23 17:38:20, Jacob Pratt via tz wrote:
> That's why I've said "where possible" or similar in previous messages.
> lastX can't be replaced, but Sun>=8 24:00 could be replaced by Mon>=9 0:00.

Yes, but "the second Sunday at 24:00" can't be replaced by
"Monday at 00:00" because that may be either the second
Monday or the third.  The code to handle the hard case must
exist; it's easy to branch around it when hour<24:00.

-- 
gil