Make the sourceModel property a QObject*

This works perfectly fine with the more specific type on Linux, but breaks
on Android for unknown reasons, making the application fail to start there.

src/map-publictransport-integration/locationqueryoverlayproxymodel.cpp

@@ -49,18 +49,18 @@ void LocationQueryOverlayProxyModel::setMapData(const MapData &data)
     emit mapDataChanged();
 }
 
-QAbstractItemModel* LocationQueryOverlayProxyModel::sourceModel() const
+QObject* LocationQueryOverlayProxyModel::sourceModel() const
 {
     return m_sourceModel;
 }
 
-void LocationQueryOverlayProxyModel::setSourceModel(QAbstractItemModel *sourceModel)
+void LocationQueryOverlayProxyModel::setSourceModel(QObject *sourceModel)
 {
     if (m_sourceModel == sourceModel) {
         return;
     }
     beginResetModel();
-    m_sourceModel = sourceModel;
+    m_sourceModel = qobject_cast<QAbstractItemModel*>(sourceModel);
     initialize();
     endResetModel();
 

src/map-publictransport-integration/locationqueryoverlayproxymodel.h

@@ -24,7 +24,7 @@ class LocationQueryOverlayProxyModel : public QAbstractListModel
 {
     Q_OBJECT
     Q_PROPERTY(KOSMIndoorMap::MapData mapData READ mapData WRITE setMapData NOTIFY mapDataChanged)
-    Q_PROPERTY(QAbstractItemModel* sourceModel READ sourceModel WRITE setSourceModel NOTIFY sourceModelChanged)
+    Q_PROPERTY(QObject* sourceModel READ sourceModel WRITE setSourceModel NOTIFY sourceModelChanged)
 
 public:
     explicit LocationQueryOverlayProxyModel(QObject *parent = nullptr);
@@ -33,8 +33,8 @@ public:
     MapData mapData() const;
     void setMapData(const MapData &data);
 
-    QAbstractItemModel *sourceModel() const;
-    void setSourceModel(QAbstractItemModel *sourceModel);
+    QObject *sourceModel() const;
+    void setSourceModel(QObject *sourceModel);
 
     enum Role {
         ElementRole = Qt::UserRole,