Issue 204

[u5surf]

Fixes #204
I fixed tiny syntax error which has occurred in ngx_http_vhost_traffic_status_string.c.
After that I confirmed make in nginx with the module which is including this fix.

% ./objs/nginx -V
nginx version: nginx/1.21.2
built by clang 11.0.0 (clang-1100.0.33.8)
configure arguments: --add-module=/Users/yugo-horie/nginx-module-vts