Fix: Picker window 'used' filter for rail waypoints

The first two field of struct PickerItem were not populated.
These are required for set operations.

StationUsesDefaultType always returned false for rail waypoints.

src/rail_gui.cpp

@@ -1151,7 +1151,7 @@ static void HandleStationPlacement(TileIndex start, TileIndex end)
 static bool StationUsesDefaultType(const BaseStation *bst)
 {
 	for (TileIndex t : bst->train_station) {
-		if (bst->TileBelongsToRailStation(t) && IsRailStation(t) && GetCustomStationSpecIndex(t) == 0) return true;
+		if (bst->TileBelongsToRailStation(t) && HasStationRail(t) && GetCustomStationSpecIndex(t) == 0) return true;
 	}
 	return false;
 }
@@ -2263,7 +2263,7 @@ public:
 			}
 			for (const auto &sm : wp->speclist) {
 				if (sm.spec == nullptr) continue;
-				items.insert({0, 0, sm.spec->class_index, sm.spec->index});
+				items.insert({sm.grfid, sm.localidx, sm.spec->class_index, sm.spec->index});
 			}
 		}
 	}