MINOR: dns: Don't set the check port during a server dns resolution

When a server dns resolution is performed, there is no reason to set an
unconfigured check port with the server port. Because by default, if the
check port is not set, the server's one is used. Thus we can remove this
useless assignment. It is mandatory for next improvements.
diff --git a/src/dns.c b/src/dns.c
index 8c97df4..69045ce 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -712,9 +712,6 @@
 
 				srv->svc_port = item->port;
 				srv->flags   &= ~SRV_F_MAPPORTS;
-				if ((srv->check.state & CHK_ST_CONFIGURED) &&
-				    !(srv->flags & SRV_F_CHECKPORT))
-					srv->check.port = item->port;
 
 				if (!srv->dns_opts.ignore_weight) {
 					char weight[9];