Add GBB flags for disabling software sync and defaulting to legacy boot

1) GBB flag to skip EC software sync, so EC will be untouched.  Needed
for EC development.

2) GBB flag to default to booting legacy at end of dev screen timeout.
Very handy for booting Ubuntu (or other OS).

Also added unit tests for the new flags.

BUG=chrome-os-partner:20111
BRANCH=link
TEST=manual
TEST=make runtests

Original-Change-Id: I9da87d87014881a1b1393b0b4a5acb921d080066
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/58270
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
(cherry picked from commit f2a1dc0a54ec542dd4be7b634483de317c89a2a2)
[cernekee: reverted to Googley 2-space indents; removed test cases that
 had nowhere to live]

Change-Id: I688cd48a23c00ae450f7f2b4b46f6d66659ff461
Reviewed-on: https://chromium-review.googlesource.com/290426
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Queue: Kevin Cernekee <cernekee@chromium.org>
Tested-by: Kevin Cernekee <cernekee@chromium.org>
3 files changed