Updating submodules
Updating submodules

Summary:
GitHub commits:

https://github.com/facebook/folly/commit/6b58b9e81875d92ba53add248d113593b24d2c8b
https://github.com/facebookexternal/stl_tasks/commit/ace5804762922bdd3113fc7de20bac3b490e52ea
https://github.com/facebookincubator/velox/commit/0a1f11f31a562438f86dbf60dd609b58963c5788

Reviewed By: bigfootjon

fbshipit-source-id: 6d6ea54b5c477f844ffea401f1664ac32fd47bac

facebook/wangle,facebook/wangle,facebook/wangle