Fix msvc warnings

src/main.cpp

@@ -159,6 +159,7 @@ void sigabrtHandler(int) {
 
 #ifndef DISABLE_GUI
 void useStyle(QApplication *app, QString style){
+  Q_UNUSED(app);
   if(!style.isEmpty()) {
     QApplication::setStyle(QStyleFactory::create(style));
   }

src/trackerlist.h

@@ -36,13 +36,11 @@
 
 #include <libtorrent/version.hpp>
 #include "qtorrenthandle.h"
+#include "propertieswidget.h"
 
 enum TrackerListColumn {COL_URL, COL_STATUS, COL_PEERS, COL_MSG};
 #define NB_STICKY_ITEM 3
 
-struct QTreeWidgetItem;
-struct PropertiesWidget;
-
 class TrackerList: public QTreeWidget {
   Q_OBJECT