MINOR: quic: add version field on quic_rx_packet

Add a new field version on quic_rx_packet structure. This is set on
header parsing in qc_lstnr_pkt_rcv() function.

This change has no functional impact. It is a part of a refactoring
series on qc_lstnr_pkt_rcv(). The objective is facilitate integration of
FD-owned socket patches.

This should be backported up to 2.6.

include/haproxy/quic_conn-t.h

@@ -395,7 +395,11 @@ struct quic_dgram {
 struct quic_rx_packet {
 	struct list list;
 	struct list qc_rx_pkt_list;
+
+	/* QUIC version used in packet. */
+	const struct quic_version *version;
 	struct quic_conn *qc;
+
 	unsigned char type;
 	/* Initial desctination connection ID. */
 	struct quic_cid dcid;