Builds a number of utilities that are used in Pyrex builds so that they don't have to be compiled on the fly when the Docker image is built. All utilities are statically linked to avoid the need for any dependencies
This is part of the util-linux package and is useful for dropping permissions in images. It was added to util-linux fairly recently and thus is not present in Ubuntu 16.04 or 14.04
Compiles tini with a custom patch required for post-processing commands (see krallin/tini#129)
Builds a bleeding edge version of icecream to fix a bug in the latest release