GitLab

Includes changes to:
- Deprecate the MX_PORT_OPT_V2 option.
- Remove various empty header files previously provided to aid porting
  of Linux code (e.g. sys/syscalls.h).

Bug: 707030
Change-Id: Ibb56470f791036037be69a341ebb716825b16b40
Reviewed-on: https://chromium-review.googlesource.com/572883
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487345}