/*
 * Save an Imlib2::Image to a file (error returned as number).
 * 
 * Provides access to the low-level imlib_save_image_with_error_return()
 * call.  You probably want to use Imlib2::Image::save() instead.
 *
 * Examples:
 *   error = image.save_with_error_return 'output_file.png'
 *   puts 'an error occurred' unless error == 0
 *
 */
static VALUE image_save_with_error_return(VALUE self, VALUE val) {