MINOR: mux-quic: save proxy instance into qcc

Store a reference to proxy in the qcc structure. This will be useful to
access to proxy members outside of qcc_init().

Most notably, this change is required to implement timeout refreshing by
using the various timeouts configured at the proxy level.

include/haproxy/mux_quic-t.h

@@ -91,6 +91,8 @@ struct qcc {
 	struct wait_event wait_event;  /* To be used if we're waiting for I/Os */
 	struct wait_event *subs;
 
+	struct proxy *proxy;
+
 	/* haproxy timeout management */
 	struct task *task;
 	int timeout;

src/mux_quic.c

@@ -1815,6 +1815,7 @@ static int qc_init(struct connection *conn, struct proxy *prx,
 	qcc->wait_event.tasklet->context = qcc;
 	qcc->wait_event.events = 0;
 
+	qcc->proxy = prx;
 	/* haproxy timeouts */
 	qcc->task = NULL;
 	qcc->timeout = prx->timeout.client;