Merge of r4915, r4916, r4917: upstream minor fixes. *) Upstream: honor the "down" flag for a single server. If an upstream block was defined with the only server marked as "down", e.g. upstream u { server 127.0.0.1:8080 down; } an attempt was made to contact the server despite the "down" flag. It is believed that immediate 502 response is better in such a case, and it's also consistent with what is currently done in case of multiple servers all marked as "down". *) Upstream: better detection of connect() failures with kqueue. Pending EOF might be reported on both read and write events, whichever comes first, so check both of them. Patch by Yichun Zhang (agentzh), slightly modified.

scgi_param  REQUEST_METHOD     $request_method;
scgi_param  REQUEST_URI        $request_uri;
scgi_param  QUERY_STRING       $query_string;
scgi_param  CONTENT_TYPE       $content_type;

scgi_param  DOCUMENT_URI       $document_uri;
scgi_param  DOCUMENT_ROOT      $document_root;
scgi_param  SCGI               1;
scgi_param  SERVER_PROTOCOL    $server_protocol;
scgi_param  HTTPS              $https if_not_empty;

scgi_param  REMOTE_ADDR        $remote_addr;
scgi_param  REMOTE_PORT        $remote_port;
scgi_param  SERVER_PORT        $server_port;
scgi_param  SERVER_NAME        $server_name;