Sync program preferences before computer shutdown to avoid loss

Changelog

@@ -3,6 +3,7 @@
     - BUGFIX: Fix possible crash when changing the priority of a file
     - BUGFIX: Magnet link association fix on Win32 (sledgehammer999)
     - BUGFIX: Easier compilation on Win32 using MinGW (sledgehammer999)
+    - BUGFIX: Sync program preferences before computer shutdown to avoid loss
     - I18N: Updated German, Italian, Hungarian, Portuguese, Brazilian, 
       Spanish and Catalan translations
 

src/qtlibtorrent/qbtsession.cpp

@@ -2111,6 +2111,8 @@ void QBtSession::readAlerts() {
               saveSessionState();
               qDebug("Saving fast resume data");
               saveFastResumeData();
+              // Make sure preferences are synced before exiting
+              pref.sync();
               qDebug("Sending computer shutdown/suspend signal");
               misc::shutdownComputer(suspend);
             }