BUG/MINOR: trace/quic: make "qconn" selectable as a lockon criterion

The test was was performed but there's no way to set the option! Let's
just add "qconn" to select the quic conn when the source supports it.

This can be backported at least to 3.0, probably 2.6.

(cherry picked from commit 7a22fbd453d7ef732b72c1d45d0e2c4f89b43fcb)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 1c44929ed16a76aa871f1221e6d369117932be16)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit cdf51d01cfda348cf8e76763b98816c5e44a110f)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/trace.c b/src/trace.c
index e5da88e..84c50c7 100644
--- a/src/trace.c
+++ b/src/trace.c
@@ -596,7 +596,11 @@
 			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_STRM))
 				chunk_appendf(&trash, "  %c server     : lock on the server that started the trace\n",
 				              src->lockon == TRACE_LOCKON_SERVER ? '*' : ' ');
-
+#ifdef USE_QUIC
+			if (src->arg_def & TRC_ARGS_QCON)
+				chunk_appendf(&trash, "  %c qconn      : lock on the QUIC connection that started the trace\n",
+				              src->lockon == TRACE_LOCKON_QCON ? '*' : ' ');
+#endif
 			if (src->arg_def & (TRC_ARGS_CONN|TRC_ARGS_QCON|TRC_ARGS_SESS|TRC_ARGS_STRM))
 				chunk_appendf(&trash, "  %c session    : lock on the session that started the trace\n",
 				              src->lockon == TRACE_LOCKON_SESSION ? '*' : ' ');
@@ -668,6 +672,10 @@
 			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_SESSION);
 			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
 		}
+		else if ((src->arg_def & TRC_ARGS_QCON) && strcmp(name, "qconn") == 0) {
+			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_QCON);
+			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);
+		}
 		else if ((src->arg_def & TRC_ARGS_STRM) && strcmp(name, "stream") == 0) {
 			HA_ATOMIC_STORE(&src->lockon, TRACE_LOCKON_STREAM);
 			HA_ATOMIC_STORE(&src->lockon_ptr, NULL);