public extern static void hb_font_funcs_set_variation_glyph_func(hb_font_funcs_t ffuncs, VariationGlyphProxyDelegate func, IntPtr user_data, hb_destroy_func_t destroy);
public extern static void hb_font_funcs_set_variation_glyph_func(IntPtr ffuncs, VariationGlyphProxyDelegate func, IntPtr user_data, ReleaseDelegateProxyDelegate destroy);