Bugfix: GUI: Delete m_taskbar_button in destructor

Author: kwsantiago

src/qt/bitcoingui.cpp

@@ -251,6 +251,9 @@ BitcoinGUI::~BitcoinGUI()
     delete m_app_nap_inhibitor;
     MacDockIconHandler::cleanup();
 #endif
+#ifdef BITCOIN_QT_WIN_TASKBAR
+    delete m_taskbar_button;
+#endif
 
     delete NetWatch;
     delete rpcConsole;