(PECL pecl_http >= 0.10.0)
HttpMessage::addHeaders — Add headers
Add headers. If append is true, headers with the same name will be separated, else overwritten.
associative array containing the additional HTTP headers to add to the messages existing headers
if true, and a header with the same name of one to add exists already, this respective header will be converted to an array containing both header values, otherwise it will be overwritten with the new header value
成功时返回 TRUE, 或者在失败时返回 FALSE.