MINOR: mux-h2: add trace on extended connect usage

Add a state trace to report that a protocol upgrade is converted using
the rfc8441 Extended connect method. This is useful in regards with the
recent changes to improve http/2 websockets.

(cherry picked from commit e0c258c84d57765c50a3e9e5a243f954474462f7)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/mux_h2.c b/src/mux_h2.c
index d8a439b..9ce6cf1 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -5318,6 +5318,7 @@
 				do {
 					if (isteqi(iststop(connection_ist, ','),
 					           ist("upgrade"))) {
+						TRACE_STATE("convert upgrade to extended connect method", H2_EV_TX_FRAME|H2_EV_TX_HDR, h2c->conn, h2s);
 						h2s->flags |= (H2_SF_BODY_TUNNEL|H2_SF_EXT_CONNECT_SENT);
 						sl->info.req.meth = HTTP_METH_CONNECT;
 						meth = ist("CONNECT");