futility: updater: support external flashrom

The libflashrom is still different from the real flashrom program.
To easily debug and compare the execution results (especially for
devices under development), we want to allow the updater to
switch between the libflashrom and the external flashrom.
The real switch (either a quirk or a command line argument) will
be added in a follow up change.

TEST=build and run test

Change-Id: I3f3226fd555dc9e7c40838cd1474e0d018b27ccc
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3500339
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Commit-Queue: Yu-Ping Wu <yupingso@chromium.org>
1 file changed