tdf#125934 Qt5 set the desktop file name

This is a preliminary fix, so LO on Wayland has an application
icon at all. As the result, the start center icon will appear as
the application icon on Wayland for all windows.

For the proper, per QWindow fix, we need some QtCore and QtWayland
changes, to allow setting the appId per QWindow and eventually a
Waylnad XDG shell spec update, to officially allow a top level
window to change its appId.

Change-Id: Icefcfc992836e0c657237984d7d88561b26b06a2
Reviewed-on: https://gerrit.libreoffice.org/74097
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>
diff --git a/vcl/inc/qt5/Qt5Instance.hxx b/vcl/inc/qt5/Qt5Instance.hxx
index 6c4afd3..2411cdb 100644
--- a/vcl/inc/qt5/Qt5Instance.hxx
+++ b/vcl/inc/qt5/Qt5Instance.hxx
@@ -65,6 +65,7 @@
    bool m_bUpdateFonts;

    DECL_LINK(updateStyleHdl, Timer*, void);
    void AfterAppInit() override;

private Q_SLOTS:
    bool ImplYield(bool bWait, bool bHandleAllCurrentEvents);
diff --git a/vcl/qt5/Qt5Instance.cxx b/vcl/qt5/Qt5Instance.cxx
index df6b903..7961d5b 100644
--- a/vcl/qt5/Qt5Instance.cxx
+++ b/vcl/qt5/Qt5Instance.cxx
@@ -241,6 +241,12 @@
    m_pQApplication.reset();
}

void Qt5Instance::AfterAppInit()
{
    // sets the default application icon on Wayland
    QGuiApplication::setDesktopFileName(QStringLiteral("libreoffice-startcenter.desktop"));
}

void Qt5Instance::deleteObjectLater(QObject* pObject) { pObject->deleteLater(); }

SalFrame* Qt5Instance::CreateChildFrame(SystemParentData* /*pParent*/, SalFrameStyleFlags nStyle)