Revert merge pull request #528

This reverts commit 70a9b93c6c0cb6d2666422905340a1708e694319, reversing
changes made to ec9d63dae69778f2cbeba86d7c33d4b872dcce2f.
Merge pull request #656 from taketwo/revert-528

Revert merge pull request #528
Add missing include directive for boost/chrono.hpp.
Merge pull request #671 from j-oberlaender/master

Add missing include directive for boost/chrono.hpp.