This is similar in purpose to the upstream
https://github.com/pyca/infra project where dockerfiles for building
custom manylinux builder images are kept. I would like to try
building manylinux2014_aarch64 images, so need an untrusted project to
do that with speculative testing.
Change-Id: I2da4e73c92dc46429fa52dd7b7b924458ad3832e