year 2038-problem

https://github.com/HaxeFoundation/neko/blob/c580c3654e49e890b364733a51fcbe2d3689c42e/libs/std/date.c#L31
defines `date_set_day` and `date_set_hour` with 32-bit integers, so if it is a signed integer, these will overflow in the year 2038. If unsigned, it would be good til 2106.

This issue was found while reviewing potential year-2038 issues in openSUSE.

Start in libs/std/date.c at line 31, where date_set_day and date_set_hour are defined, and inspect the integer types and their callers. Determine whether the current representation can overflow around 2038, then verify that the date setters support the intended range without overflow.

Written by the indexing model from the issue text.