Win32: detection of connect() errors in select(). On Windows, connect() errors are only reported via exceptfds descriptor set from select(). Previously exceptfds was set to NULL, and connect() errors were not detected at all, so connects to closed ports were waiting till a timeout occurred. Since ongoing connect() means that there will be a write event active, except descriptor set is copied from the write one. While it is possible to construct except descriptor set as a concatenation of both read and write descriptor sets, this looks unneeded. With this change, connect() errors are properly detected now when using select(). Note well that it is not possible to detect connect() errors with WSAPoll() (see https://daniel.haxx.se/blog/2012/10/10/wsapoll-is-broken/).

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  REQUEST_SCHEME     $scheme;
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;