smpp_vty: Ensure to not print 'system-id' in openbsc.cfg if its empty
... as an empty system-id would render the openbsc.cfg unparseable on
next openbsc start.
diff --git a/openbsc/src/libmsc/smpp_vty.c b/openbsc/src/libmsc/smpp_vty.c
index c6bb74d..96447bf 100644
--- a/openbsc/src/libmsc/smpp_vty.c
+++ b/openbsc/src/libmsc/smpp_vty.c
@@ -119,7 +119,8 @@
vty_out(vty, "smpp%s", VTY_NEWLINE);
vty_out(vty, " local-tcp-port %u%s", smsc->listen_port, VTY_NEWLINE);
- vty_out(vty, " system-id %s%s", smsc->system_id, VTY_NEWLINE);
+ if (smsc->system_id)
+ vty_out(vty, " system-id %s%s", smsc->system_id, VTY_NEWLINE);
vty_out(vty, " policy %s%s",
smsc->accept_all ? "accept-all" : "closed", VTY_NEWLINE);