tdf#94384 fix black icons with OpenGL enabled on Windows

Looks like the Windows specific code in ImplUpdateDisplayBmp is
not needed anymore and causes problems with OpenGL. The icons after
the change still seem to be drawn correctly with OpenGL enabled
or disabled.

Change-Id: I3ae1a0ceb947254aaadbc3d772f0d662b291b594

vcl/source/gdi/impimage.cxx

@@ -328,28 +328,11 @@ void ImplImageBmp::Draw( OutputDevice* pOutDev,
     }
 }
 
-void ImplImageBmp::ImplUpdateDisplayBmp( OutputDevice*
-#if defined WNT
-pOutDev
-#endif
-)
+void ImplImageBmp::ImplUpdateDisplayBmp(OutputDevice*)
 {
-    if( !mpDisplayBmp && !maBmpEx.IsEmpty() )
+    if (!mpDisplayBmp && !maBmpEx.IsEmpty())
     {
-#if defined WNT
-        if( !maBmpEx.IsAlpha() )
-        {
-            // FIXME: this looks like rather an obsolete code-path to me.
-            const Bitmap aBmp( maBmpEx.GetBitmap().CreateDisplayBitmap( pOutDev ) );
-
-            if( maBmpEx.IsTransparent() )
-                mpDisplayBmp = new BitmapEx( aBmp, maBmpEx.GetMask().CreateDisplayBitmap( pOutDev ) );
-            else
-                mpDisplayBmp = new BitmapEx( aBmp );
-        }
-        else
-#endif
-            mpDisplayBmp = new BitmapEx( maBmpEx );
+        mpDisplayBmp = new BitmapEx(maBmpEx);
     }
 }