Set adjacent crossings setting to false when loading pre v300 trunk savegames

src/saveload/afterload.cpp

@@ -3814,6 +3814,8 @@ bool AfterLoadGame()
 
 	if (!IsSavegameVersionBefore(SLV_MULTITRACK_LEVEL_CROSSINGS)) {
 		_settings_game.vehicle.adjacent_crossings = true;
+	} else if (SlXvIsFeatureMissing(XSLFI_ADJACENT_CROSSINGS)) {
+		_settings_game.vehicle.adjacent_crossings = false;
 	}
 
 	/* Compute station catchment areas. This is needed here in case UpdateStationAcceptance is called below. */