Change: Treat extended waypoint classes as 'WAYP' class.

This maps the extended custom waypoint clases (where the first byte of the label is 0xFF)
to the standard 'WAYP' label, allowing use of them before the feature
exists.

src/newgrf.cpp

@@ -1944,8 +1944,9 @@ static ChangeInfoResult StationChangeInfo(uint stid, int numinfo, int prop, Byte
 				}
 
 				/* Swap classid because we read it in BE meaning WAYP or DFLT */
-				uint32_t classid = buf->ReadDWord();
-				statspec->cls_id = StationClass::Allocate(BSWAP32(classid));
+				uint32_t classid = BSWAP32(buf->ReadDWord());
+				if (GB(classid, 24, 8) == 0xFF) classid = 'WAYP';
+				statspec->cls_id = StationClass::Allocate(classid);
 				break;
 			}
 
@@ -4789,8 +4790,9 @@ static ChangeInfoResult RoadStopChangeInfo(uint id, int numinfo, int prop, ByteR
 					rs = _cur.grffile->roadstops[id + i].get();
 				}
 
-				uint32_t classid = buf->ReadDWord();
-				rs->cls_id = RoadStopClass::Allocate(BSWAP32(classid));
+				uint32_t classid = BSWAP32(buf->ReadDWord());
+				if (GB(classid, 24, 8) == 0xFF) classid = 'WAYP';
+				rs->cls_id = RoadStopClass::Allocate(classid);
 				break;
 			}