Replace include of <libtorrent/session.hpp> with forward declaration

src/geoip/geoipmanager.cpp

@@ -65,6 +65,7 @@
 #include <QChar>
 
 #include "fs_utils.h"
+#include <libtorrent/session.hpp>
 
 using namespace libtorrent;
 

src/geoip/geoipmanager.h

@@ -31,10 +31,13 @@
 #ifndef GEOIPMANAGER_H
 #define GEOIPMANAGER_H
 
-#include <libtorrent/session.hpp>
 #include <QString>
 #include <QIcon>
 
+namespace libtorrent {
+  class session;
+}
+
 class GeoIPManager : public QObject {
   Q_OBJECT