A fork for the time-zone database?

Martian sols are not 24 hours long, so you would need to change the UTC offset every sol (Martian day) to keep it in sync. The least-bad way to do that is probably a set of DST rules configured such that a new DST offset takes effect at the end of each sol, but that would take up a prohibitive number of entries in the tzdb. And I'm not sure if you could even reuse those entries next year, because the Martian calendar would fall out of sync with the terrestrial calendar, so you'd need a new set of DST rules for each year. You could probably write software to automatically generate these entries, but at that point you might as well not use tzdb in the first place.