windows opengl: Don't paint cached widgets upside down.

Change-Id: Idf1e4bd06c2c6d2371c634e68baf4fd0a7763cb1
Reviewed-on: https://gerrit.libreoffice.org/18233Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>

vcl/opengl/win/gdiimpl.cxx

@@ -78,9 +78,9 @@ bool WinOpenGLSalGraphicsImpl::TryRenderCachedNativeControl(ControlCacheKey& rCo
                        nX, nY, rTexture.GetWidth(), rTexture.GetHeight());
 
     if (pCombo->mpMask)
-        DrawTextureDiff(rTexture, *pCombo->mpMask, aPosAry, true);
+        DrawTextureDiff(rTexture, *pCombo->mpMask, aPosAry);
     else
-        DrawTexture(rTexture, aPosAry, true);
+        DrawTexture(rTexture, aPosAry);
 
     PostDraw();