Fix build with llvm 19
https://github.com/OpenTTD/OpenTTD/pull/12876

Index: src/pathfinder/yapf/yapf_road.cpp
--- src/pathfinder/yapf/yapf_road.cpp.orig
+++ src/pathfinder/yapf/yapf_road.cpp
@@ -462,7 +462,7 @@ class CYapfFollowRoadT (public)
 		/* set origin (tile, trackdir) */
 		TileIndex src_tile = v->tile;
 		Trackdir src_td = v->GetVehicleTrackdir();
-		if (!HasTrackdir(GetTrackdirBitsForRoad(src_tile, this->IsTram() ? RTT_TRAM : RTT_ROAD), src_td)) {
+		if (!HasTrackdir(GetTrackdirBitsForRoad(src_tile, Yapf().IsTram() ? RTT_TRAM : RTT_ROAD), src_td)) {
 			/* sometimes the roadveh is not on the road (it resides on non-existing track)
 			 * how should we handle that situation? */
 			return false;
