stats: Make net config optional

To support reporters without network configuration, this commit
introduces the have_net_config flag to provide corresponding error
messages.

Sponsored-by: On-Waves ehf
diff --git a/src/vty/stats_vty.c b/src/vty/stats_vty.c
index 0911fbb..18ad283 100644
--- a/src/vty/stats_vty.c
+++ b/src/vty/stats_vty.c
@@ -281,18 +281,21 @@
 
 	vty_out(vty, "  disable%s", VTY_NEWLINE);
 
-	if (srep->dest_addr_str)
-		vty_out(vty, "  remote-ip %s%s",
-			srep->dest_addr_str, VTY_NEWLINE);
-	if (srep->dest_port)
-		vty_out(vty, "  remote-port %d%s",
-			srep->dest_port, VTY_NEWLINE);
-	if (srep->bind_addr_str)
-		vty_out(vty, "  local-ip %s%s",
-			srep->bind_addr_str, VTY_NEWLINE);
-	if (srep->mtu)
-		vty_out(vty, "  mtu %d%s",
-			srep->mtu, VTY_NEWLINE);
+	if (srep->have_net_config) {
+		if (srep->dest_addr_str)
+			vty_out(vty, "  remote-ip %s%s",
+				srep->dest_addr_str, VTY_NEWLINE);
+		if (srep->dest_port)
+			vty_out(vty, "  remote-port %d%s",
+				srep->dest_port, VTY_NEWLINE);
+		if (srep->bind_addr_str)
+			vty_out(vty, "  local-ip %s%s",
+				srep->bind_addr_str, VTY_NEWLINE);
+		if (srep->mtu)
+			vty_out(vty, "  mtu %d%s",
+				srep->mtu, VTY_NEWLINE);
+	}
+
 	if (srep->name_prefix && *srep->name_prefix)
 		vty_out(vty, "  prefix %s%s",
 			srep->name_prefix, VTY_NEWLINE);