Remove dead SalDisplay::GetSalDisplay declaration

Change-Id: Ib24e857b19ceb6ca721b537351e95379a0992640
diff --git a/vcl/inc/unx/saldisp.hxx b/vcl/inc/unx/saldisp.hxx
index 896ac52..8b56e18 100644
--- a/vcl/inc/unx/saldisp.hxx
+++ b/vcl/inc/unx/saldisp.hxx
@@ -288,7 +288,6 @@ protected:
    void            doDestruct();
    void            addXineramaScreenUnique( int i, long i_nX, long i_nY, long i_nWidth, long i_nHeight );
public:
    static SalDisplay *GetSalDisplay( Display* display );
    static bool BestVisual( Display     *pDisp,
                                int          nScreen,
                                XVisualInfo &rVI );