Don't use wxMSW wxAppProgressIndicator if wxUSE_TASKBARBUTTON==0.

This class requires wxTaskBarButton to be really implemented, so there is no
need to even define the MSW-specific version of it if wxUSE_TASKBARBUTTON is 0
anyhow.

This fixes a compilation problem with wxUSE_TASKBARBUTTON==0 but, more
importantly, just makes more sense.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77745 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/appprogress.h

@@ -31,9 +31,7 @@ public:
 private:
     int m_maxValue;
 
-#if wxUSE_TASKBARBUTTON
     wxVector<wxTaskBarButton*> m_taskBarButtons;
-#endif  // wxUSE_TASKBARBUTTON
 
     wxDECLARE_NO_COPY_CLASS(wxAppProgressIndicator);
 };