(png_instantiate):

(png_instantiate):
- Use `png_get_image_height (png_ptr, info_ptr)' instead of
  `info_ptr->height'.
- Use `png_get_image_width (png_ptr, info_ptr)' instead of
  `info_ptr->width'.
- Use `png_get_color_type(png_ptr, info_ptr)' instead of
  `info_ptr->color_type'.
- Use `png_get_bit_depth(png_ptr, info_ptr)' instead of
  `info_ptr->bit_depth'.