Callback formerly fired on the save_post hook. No longer needed.

function _save_post_hook() {}

/**
 * Check if the installed version of GD supports particular image type
 *
 * @since 2.9.0
 * @deprecated 3.5.0 Use wp_image_editor_supports()
 * @see wp_image_editor_supports()
 *
 * @param string $mime_type
 * @return bool
 */