修正HTTP流式发送应答时，Content-Length填写错误的问题。

plugin/protocol/http/src/http_half.cpp

@@ -971,7 +971,7 @@ void hf_private_construct(struct http_half_private * hf_private)
 	}
 
 	/* have body, write content-length and content-type */
-	if (hf_private->evbuf_body)
+	if (hf_private->evbuf_body && !hf_private->is_setup_by_stream)
 	{
 		/* To string */
 		char str_sz_evbuf_body[TFE_STRING_MAX];