/*
 * call-seq:
 *   easy.header_in_body = boolean                    => boolean
 *
 * Configure whether this Curl instance will return HTTP headers
 * combined with body data. If this option is set true, both header
 * and body data will go to +body_str+ (or the configured +on_body+ handler).
 */
static VALUE ruby_curl_easy_header_in_body_set(VALUE self, VALUE header_in_body) {