Make vbutil_kernel use correct size when verifying headers.

Added a test to demonstrate the fix.

BUG=none
TEST=manual

make
make runtests

Change-Id: I06e85b993cbe21088641a62d55a3d3ddb696ba76
Reviewed-on: https://gerrit.chromium.org/gerrit/18240
Commit-Ready: Bill Richardson <wfrichar@chromium.org>
Tested-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
3 files changed