Fix Library_vclplug_qt5

...after 8bc951da "long->sal_Int32 in
tools/gen.hxx".  (According to <https://doc.qt.io/qt-5/qwidget.html>,
QtWidget::height and QtWidget::width both return int, so the change should be
OK, assuming int isn't larger than sal_Int32.)

Change-Id: I847212db59cceb49743801d6cc204eb7b2e9ea9a

vcl/qt5/Qt5Frame.cxx

@@ -318,7 +318,7 @@ void Qt5Frame::SetPosSize(long nX, long nY, long nWidth, long nHeight, sal_uInt1
     m_bDefaultPos = false;
 }
 
-void Qt5Frame::GetClientSize(long& rWidth, long& rHeight)
+void Qt5Frame::GetClientSize(sal_Int32& rWidth, sal_Int32& rHeight)
 {
     rWidth = m_pQWidget->width();
     rHeight = m_pQWidget->height();

vcl/qt5/Qt5Frame.hxx

@@ -96,7 +96,7 @@ public:
     virtual void SetMaxClientSize(long nWidth, long nHeight) override;
     virtual void SetPosSize(long nX, long nY, long nWidth, long nHeight,
                             sal_uInt16 nFlags) override;
-    virtual void GetClientSize(long& rWidth, long& rHeight) override;
+    virtual void GetClientSize(sal_Int32& rWidth, sal_Int32& rHeight) override;
     virtual void GetWorkArea(tools::Rectangle& rRect) override;
     virtual SalFrame* GetParent() const override;
     virtual void SetWindowState(const SalFrameState* pState) override;