Industry::this_month_production should saturate instead of overflowing

src/industry_cmd.cpp

@@ -544,7 +544,7 @@ static bool TransportIndustryGoods(TileIndex tile)
 			/* fluctuating economy? */
 			if (EconomyIsInRecession()) cw = (cw + 1) / 2;
 
-			i->this_month_production[j] += cw;
+			i->this_month_production[j] = std::min<uint>(i->this_month_production[j] + cw, 0xFFFF);
 
 			uint am = MoveGoodsToStation(i->produced_cargo[j], cw, ST_INDUSTRY, i->index, &i->stations_near, i->exclusive_consumer);
 			i->this_month_transported[j] += am;