Change the mkimage script so that the produced image is
reproducible. This involves:
- removing the ldconfig aux-cache as it changes on every build.
- set the mtimes of the files to a specific date so that the
resulting tar file will have the same contents.
- The `strings` guard around the unsafe-io tweak seems to be
non-deterministic. It was sometimes not adding the tweak
for the same file. Remove it as we don't care about older
than jessie.
- Importing the image by constructing a docker image with
a specific timestamp and doing `docker load`.
Also change the buildall script to build each image twice and
confirm that the same tarball is produced, and that results
in the layers in the imported images matching.
Add a dockerdiff script that checks that two images are equivalent,
and tries to show the differences if not. This is useful when the
build script reports differences, as it can point to what the
differences are.
James Westby