gcc 5.4.0 doesn't support atomic_##type

Bug: 
Change-Id: I31d112097b6236299caf86bfc7a34888cbe65e39
Reviewed-on: https://chromium-review.googlesource.com/757178Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#49205}