Collection: Always use Idle priority for watcher

src/collection/collection.h

@@ -28,11 +28,10 @@
 #include <QList>
 #include <QHash>
 #include <QString>
-#include <QThread>
 
 #include "core/song.h"
-#include "utilities/threadutils.h"
 
+class QThread;
 class Application;
 class Thread;
 class CollectionBackend;
@@ -99,8 +98,6 @@ class SCollection : public QObject {
 
   QList<QObject*> wait_for_exit_;
 
-  Utilities::IoPriority io_priority_;
-  QThread::Priority thread_priority_;
   bool save_playcounts_to_files_;
   bool save_ratings_to_files_;
 };