Cleanup #9725: Replace cmd_helper related functions and remove cmd_helper.h.

src/road_map.h

@@ -282,6 +282,17 @@ static inline bool HasTownOwnedRoad(TileIndex t)
 	return HasTileRoadType(t, RTT_ROAD) && IsRoadOwner(t, RTT_ROAD, OWNER_TOWN);
 }
 
+/**
+ * Checks if a DisallowedRoadDirections is valid.
+ *
+ * @param wc The value to check
+ * @return true if the given value is a valid DisallowedRoadDirections.
+ */
+static inline bool IsValidDisallowedRoadDirections(DisallowedRoadDirections drt)
+{
+	return drt < DRD_END;
+}
+
 /**
  * Gets the disallowed directions
  * @param t the tile to get the directions from