CLEANUP: dns: Remove a forgotten debug message

A debug message was forgotten in the dns part.

This patch should fix the issue #1304. It must be backported to 2.4.

(cherry picked from commit c3fe968f221e2f7c63b7eb24f557223c4bbbe75f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/dns.c b/src/dns.c
index 6e0ae26..d4bf839 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -170,7 +170,6 @@
 
 		if (!LIST_ISEMPTY(&dss->wait_sess)) {
 			ds = LIST_NEXT(&dss->wait_sess, struct dns_session *, waiter);
-			fprintf(stderr, "ds: %p\n", ds);
 			ret = ds->rx_msg.len < size ? ds->rx_msg.len : size;
 			memcpy(data, ds->rx_msg.area, ret);