vboot2: Add host lib function to create a vb2-style firmware preamble

And associated unit tests

BUG=chromium:423882
BRANCH=none
TEST=VBOOT2=1 make runtests

Change-Id: I3bf6ff6c6e32dfd0dd737f9b04ff0546e9e0a463
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/231728
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
5 files changed