vboot/sign_official_build: re-sign miniOS partitions

sign_official_build.sh needs to be taught how to re-sign miniOS
partitions, depending on whether the particular image at hand
contains them or not.

BUG=b:188121855
TEST=make clean && make runtests
BRANCH=none

Cq-Depend: chromium:3027786
Signed-off-by: Joel Kitching <kitching@google.com>
Change-Id: Iaf847e14588011dd0fea6b59405091ae36ef038f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2989640
Tested-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
1 file changed