Compatibility: added segfault prevent routine for the issues/75

Author: vozlt

src/ngx_http_vhost_traffic_status_display.c

@@ -1081,6 +1081,10 @@ ngx_http_vhost_traffic_status_display_set_upstream_group(ngx_http_request_t *r,
  continue;
  }
 
+ if (us[j].addrs == NULL) {
+ continue;
+ }
+
  p = ngx_cpymem(p, uscf->host.data, uscf->host.len);
  *p++ = NGX_HTTP_VHOST_TRAFFIC_STATUS_KEY_SEPARATOR;
  p = ngx_cpymem(p, us[j].addrs->name.data, us[j].addrs->name.len);