netclientclock: send clock sync signal upon corrupted

Clients that already gotten a signal for synced clock, may rely on
getting the same when marked as corrupted to take appropriate action. So
send clock signal indicating no sync at identified corrupted state.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7664>

subprojects/gstreamer/libs/gst/net/gstnetclientclock.c

@@ -666,6 +666,7 @@ corrupted:
     self->marked_corrupted = TRUE;
   }
   GST_OBJECT_UNLOCK (self);
+  gst_clock_set_synced (GST_CLOCK (self), FALSE);
   return;
 }