Changes with nginx 1.9.8 08 Dec 2015
*) Feature: pwritev() support.
*) Feature: the "include" directive inside the "upstream" block.
*) Feature: the ngx_http_slice_module.
*) Bugfix: a segmentation fault might occur in a worker process when
using LibreSSL; the bug had appeared in 1.9.6.
*) Bugfix: nginx could not be built on OS X in some cases.