Track SCTP_STREAM_CHANGE_EVENT and display it

This notifies us if the number of streams changes while running.

Change-Id: Idccfe3e834c48582a6d7fc523262ff9ac4294f61
diff --git a/aos/network/sctp_client.cc b/aos/network/sctp_client.cc
index 91976cc..d77392e 100644
--- a/aos/network/sctp_client.cc
+++ b/aos/network/sctp_client.cc
@@ -59,6 +59,7 @@
     memset(&subscribe, 0, sizeof(subscribe));
     subscribe.sctp_data_io_event = 1;
     subscribe.sctp_association_event = 1;
+    subscribe.sctp_stream_change_event = 1;
     PCHECK(setsockopt(fd_, SOL_SCTP, SCTP_EVENTS, (char *)&subscribe,
                       sizeof(subscribe)) == 0);
   }