[PATCH] Fix multiple minor tzset glitches [BZ #24004]

[Paul Eggert]

On 4/12/19 10:07 AM, Carlos O'Donell wrote:
>> One possible compromise would be for localtime to poll, and for
>> localtime_r to not poll...
>  
> If users have to make code changes it's better to just add a new api
> for "Check for update?" and "Do the update!". 

If we add that API, will we also change localtime() to stop checking for
and doing updates in the (undocumented) cases where localtime checks for
and does them now? And if not, how will programs arrange for localtime
to be faster? This would seem to be the key question.