CMake: Do not create file system node in main thread

The file system scanning was already in a thread, but creating a tree
from the flat list of file nodes was still done in the main thread.
Creating the tree looks for and creates folder nodes as needed for each
file node, which is not that big of a deal but still takes 1/3 of a
second for the Qt Creator source tree.

Task-number: QTCREATORBUG-25783
Change-Id: I28948ed3ff5233f6fc4b86e93da94d882b81e231
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

src/plugins/cmakeprojectmanager/fileapireader.h

@@ -30,6 +30,7 @@
 #include "cmakeprojectnodes.h"
 
 #include <projectexplorer/rawprojectpart.h>
+#include <projectexplorer/treescanner.h>
 
 #include <utils/filesystemwatcher.h>
 #include <utils/optional.h>
@@ -70,7 +71,7 @@ public:
     CMakeConfig takeParsedConfiguration(QString &errorMessage);
     QString ctestPath() const;
     std::unique_ptr<CMakeProjectNode> generateProjectTree(
-        const QList<const ProjectExplorer::FileNode *> &allFiles,
+        const ProjectExplorer::TreeScanner::Result &allFiles,
         QString &errorMessage,
         bool includeHeaderNodes);
     ProjectExplorer::RawProjectParts createRawProjectParts(QString &errorMessage);