MINOR: mux-quic: define release app-ops

Define a new callback release inside qcc_app_ops. It is called when the
qcc MUX is freed via qc_release. This will allows to implement cleaning
on the app layer.

include/haproxy/mux_quic-t.h

@@ -118,6 +118,7 @@ struct qcc_app_ops {
 	int (*decode_qcs)(struct qcs *qcs, int fin, void *ctx);
 	size_t (*snd_buf)(struct conn_stream *cs, struct buffer *buf, size_t count, int flags);
 	int (*finalize)(void *ctx);
+	void (*release)(void *ctx);
 };
 
 #endif /* USE_QUIC */

src/mux_quic.c

@@ -481,6 +481,9 @@ static void qc_release(struct qcc *qcc)
 
 		TRACE_DEVEL("freeing qcc", QMUX_EV_QCC_END, conn);
 
+		if (qcc->app_ops && qcc->app_ops->release)
+			qcc->app_ops->release(qcc->ctx);
+
 		if (qcc->wait_event.tasklet)
 			tasklet_free(qcc->wait_event.tasklet);