SelectableFilesModel: Fix null pointer in internalPointer

Task-number: QTCREATORBUG-11320

Change-Id: I18154b7079e760ff363e92e2ec82542592b70e5b
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/projectexplorer/selectablefilesmodel.cpp

@@ -49,6 +49,9 @@ SelectableFilesModel::SelectableFilesModel(QObject *parent)
     : QAbstractItemModel(parent), m_root(0), m_allFiles(true)
 {
     connect(&m_watcher, SIGNAL(finished()), this, SLOT(buildTreeFinished()));
+
+    m_root = new Tree;
+    m_root->parent = 0;
 }
 
 void SelectableFilesModel::setInitialMarkedFiles(const QStringList &files)