clang-tidy clang-analyzer-deadcode.DeadStores

...at least since the commented-out code using it got removed with
99f58dc2 "vcl: remove dead code and useless task
comments from winproc.cxx"

Change-Id: Idddd3af6d667370cb937aa065382c1913ab8e911

vcl/source/window/winproc.cxx

@@ -100,7 +100,6 @@ static bool ImplHandleMouseFloatMode( vcl::Window* pChild, const Point& rMousePo
                     if ( !pFloat )
                     {
                         pLastLevelFloat = pSVData->maWinData.mpFirstFloat->ImplFindLastLevelFloat();
-                        nPopupFlags = pLastLevelFloat->GetPopupModeFlags();
                         pLastLevelFloat->EndPopupMode( FloatWinPopupEndFlags::Cancel | FloatWinPopupEndFlags::CloseAll );
                         return true;
                     }