Added compiler flags to enable Control Flow Guard. Change-Id: I86e24b83e2e9b279c93c518ab9bc7dafd4b3d006 Reviewed-on: https://chromium-review.googlesource.com/272501 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>