Remove Hildon framework support.

The Hildon framework was used for Nokia 770 and other Maemo devices.
This platform discontinued and hasn't seen a new release since 2011.

include/wx/gtk/frame.h

@@ -50,11 +50,6 @@ public:
     virtual bool ShowFullScreen(bool show, long style = wxFULLSCREEN_ALL) wxOVERRIDE;
     wxPoint GetClientAreaOrigin() const wxOVERRIDE { return wxPoint(0, 0); }
 
-#if wxUSE_LIBHILDON || wxUSE_LIBHILDON2
-    // in Hildon environment all frames are always shown maximized
-    virtual bool IsMaximized() const { return true; }
-#endif // wxUSE_LIBHILDON || wxUSE_LIBHILDON2
-
     // implementation from now on
     // --------------------------