BUG/MINOR: proto-htx: Consider a XFER_LEN message as chunked by default

An HTX message with a known body length is now considered by default as
chunked. It means the header "content-length" must be found to consider it as a
non-chunked message. Before, it was the reverse, the message was considered with
a content length by default. But it is a bug for HTTP/2 messages. There is no
chunked transfer encoding in HTTP/2 but internally messages without content
length are considered as chunked. It eases HTTP/1 <-> HTTP/2 conversions.

This patch must be backported to 1.9.
diff --git a/src/proto_htx.c b/src/proto_htx.c
index 59b7cb2..d1bdac2 100644
--- a/src/proto_htx.c
+++ b/src/proto_htx.c
@@ -312,7 +312,7 @@
 	if (sl->flags & HTX_SL_F_VER_11)
                 msg->flags |= HTTP_MSGF_VER_11;
 	msg->flags |= HTTP_MSGF_XFER_LEN;
-	msg->flags |= ((sl->flags & HTX_SL_F_CHNK) ? HTTP_MSGF_TE_CHNK : HTTP_MSGF_CNT_LEN);
+	msg->flags |= ((sl->flags & HTX_SL_F_CLEN) ? HTTP_MSGF_CNT_LEN : HTTP_MSGF_TE_CHNK);
 	if (sl->flags & HTX_SL_F_BODYLESS)
 		msg->flags |= HTTP_MSGF_BODYLESS;
 
@@ -1625,7 +1625,7 @@
                 msg->flags |= HTTP_MSGF_VER_11;
 	if (sl->flags & HTX_SL_F_XFER_LEN) {
 		msg->flags |= HTTP_MSGF_XFER_LEN;
-		msg->flags |= ((sl->flags & HTX_SL_F_CHNK) ? HTTP_MSGF_TE_CHNK : HTTP_MSGF_CNT_LEN);
+		msg->flags |= ((sl->flags & HTX_SL_F_CLEN) ? HTTP_MSGF_CNT_LEN : HTTP_MSGF_TE_CHNK);
 		if (sl->flags & HTX_SL_F_BODYLESS)
 			msg->flags |= HTTP_MSGF_BODYLESS;
 	}