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

Reviewed-on: https://chromium-review.googlesource.com/349275


Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

(cherry picked from commit a435daa1)

Change-Id: If4e30a699fdfb76e192568fff099e713990f9e47