Change default to build ChromeOS with AFDO.

Change the default USE flags to use AFDO since that is how the
released images are built. To build WITHOUT AFDO do:

  build_chromeos.py --env='USE=-afdo_use' --board ....

BUG=None
TEST=Tested building with and without AFDO. Verified right USE
     flags are generated.

Change-Id: I6ae2313b76b08fc0e0a22aae90f4ca0396d523e4
Reviewed-on: https://chrome-internal-review.googlesource.com/210834
Reviewed-by: Caroline Tice <cmtice@google.com>
Tested-by: Luis Lozano <llozano@chromium.org>
Commit-Queue: Luis Lozano <llozano@chromium.org>
1 file changed