Simplified ngx_http_init_listening().

Simplified ngx_http_init_listening().

There is no need to set "i" to 0, as it's expected to be 0 assuming
the bindings are properly sorted, and we already rely on this when
explicitly set hport->naddrs to 1.  Remaining conditional code is
replaced with identical "hport->naddrs = i + 1".

Identical modifications are done in the mail and stream modules,
in the ngx_mail_optimize_servers() and ngx_stream_optimize_servers()
functions, respectively.

No functional changes.