fixed acceptable 'state' directive contexts

[aluttik]

This was throwing an NgxParserDirectiveContextError:

http {
    upstream {
        state /path/to/state/file.conf;
    }
}

Although it shouldn't've, as you can see here:
http://nginx.org/en/docs/http/ngx_http_upstream_module.html#state
http://nginx.org/en/docs/stream/ngx_stream_upstream_module.html#state

[gshulegaard]

:1st_place_medal::dash:

[dedm]

:dash: