Fix for GCC 4.8 and above.
Fix for GCC 4.8 and above.

Summary:
GitHub Pull request
fixes facebook/squangle#2

Test Plan: Automated tests

Reviewers: fredemmott, chip, anca

Reviewed By: anca

Subscribers: anca, lins

Differential Revision: https://phabricator.fb.com/D2116739

Signature: t1:2116739:1433203661:6a207bc8ba9cc29c6d20d092721f1c5621527442

linearregression/squangle