update_engine: remove deprecated defines Glibc 2.23 will pop warning like This CL fixes that. BUG=chromium:616784 TEST=upate_engine builds with glibc 2.23 Change-Id: I871ed20dee263e94dba34d4806d46c9327155d6c Reviewed-on: https://chromium-review.googlesource.com/349275 Commit-Ready: Yunlian Jiang <[email protected]> Tested-by: Yunlian Jiang <[email protected]> Reviewed-by: Mike Frysinger <[email protected]>