Automated submodule update: velox (#332)

Summary:
This is an automated pull request to update the first-party submodule for [facebookincubator/velox](https://github.com/facebookincubator/velox).

New submodule commit: facebookincubator/velox@5e37e22

Pull Request resolved: #332

Test Plan: Ensure that CI jobs succeed on GitHub before landing.

Reviewed By: wenleix, damianr99

Differential Revision: D36476230

fbshipit-source-id: e7ee83b5566d4437dfee9e6d6ea10221ea8b8d90