Fix #11748: Incorrect clamping of negative service interval values (#11749)

(cherry picked from commit f7bd70baec)

src/order_cmd.cpp

@@ -2946,7 +2946,7 @@ void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist, bool reset_order_indic
  * @param interval proposed service interval
  * @return Clamped service interval
  */
-uint16_t GetServiceIntervalClamped(uint interval, bool ispercent)
+uint16_t GetServiceIntervalClamped(int interval, bool ispercent)
 {
 	return ispercent ? Clamp(interval, MIN_SERVINT_PERCENT, MAX_SERVINT_PERCENT) : Clamp(interval, MIN_SERVINT_DAYS, MAX_SERVINT_DAYS);
 }

src/order_func.h

@@ -46,7 +46,7 @@ static const uint DEF_SERVINT_PERCENT = 50;
 static const uint MIN_SERVINT_PERCENT = 5;
 static const uint MAX_SERVINT_PERCENT = 90;
 
-uint16_t GetServiceIntervalClamped(uint interval, bool ispercent);
+uint16_t GetServiceIntervalClamped(int interval, bool ispercent);
 bool OrderConditionCompare(OrderConditionComparator occ, int variable, int value);
 
 const char *GetOrderTypeName(OrderType order_type);