fix qt5 build

Zhao Yuhang

2023-12-14 ca6ba7d7aa547b4e0c8d86fb9e00f25374a181db

 src/quick/quickwindowagent_p.h

@@ -16,6 +16,10 @@

        // Host
        QQuickWindow *hostWindow{};

#ifdef Q_OS_WINDOWS
        void setupWindows10BorderWorkaround();
#endif
    };

}