Fix #11997: Adjust economy date by 1920 when loading TTD/TTO savegames (#12007)

src/saveload/afterload.cpp

@@ -1436,6 +1436,8 @@ bool AfterLoadGame()
 	if (IsSavegameVersionBefore(SLV_31)) {
 		TimerGameCalendar::date += CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR;
 		TimerGameCalendar::year += CalendarTime::ORIGINAL_BASE_YEAR;
+		TimerGameEconomy::date += EconomyTime::DAYS_TILL_ORIGINAL_BASE_YEAR;
+		TimerGameEconomy::year += EconomyTime::ORIGINAL_BASE_YEAR;
 
 		for (Station *st : Station::Iterate())   st->build_date      += CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR;
 		for (Waypoint *wp : Waypoint::Iterate()) wp->build_date      += CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR;