Merge remote-tracking branch 'origin/swift-4.0-branch' into stable

* origin/swift-4.0-branch:
  Merging r295224: ------------------------------------------------------------------------ r295224 | rsmith | 2017-02-15 11:57:10 -0800 (Wed, 15 Feb 2017) | 2 lines
  Merging r295313: ------------------------------------------------------------------------ r295313 | stulova | 2017-02-16 04:49:29 -0800 (Thu, 16 Feb 2017) | 9 lines
  [OpenCL][Doc] Relase 4.0 notes for OpenCL