fix build without graphics context

src/generic/activityindicator.cpp

@@ -122,7 +122,7 @@ private:
     void OnPaint(wxPaintEvent& WXUNUSED(event))
     {
         wxPaintDC pdc(m_win);
-
+#if wxUSE_GRAPHICS_CONTEXT
         wxScopedPtr<wxGraphicsContext> const
             gc(wxGraphicsRenderer::GetDefaultRenderer()->CreateContext(pdc));
 
@@ -167,6 +167,7 @@ private:
             gc->FillPath(path);
             gc->Rotate(angle);
         }
+#endif        
     }
 
     AdvanceTimer m_timer;