Track ubuntu rustc package
Tracking issue of the
ubuntu 18.04. Currently it's on v
1.18 which is too old and we can't enable the tests in the CI.
Mainly so I won't forget.
Things to do when it lands:
- Update compiling.md
- Create container images for i386/amd64/etc
- Write/Enable the CI tests
Ubuntu i386 base image: https://hub.docker.com/r/i386/ubuntu/