futility: Include libzip properly

The libzip in Makefile was not properly handled in factory branches and
need to be updated.

BUG=b:138632591
TEST=emerge-oak vboot_reference

Change-Id: I52cb15ee831d57f73b472f6c961f32cce3683294
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1729714
1 file changed