Various Linux distributions provide SBCL without core-compression
enabled. On the other hand, Mac OSX (at least via `homebrew`) SBCL with
core-compression enabled. To make installation easier, teach the make
process to detect core-compression, and use it if possible.
Apparently it's quite common nowadays for people to use docker to build
and run software in a contained way, so provide users with the facility
they need in order to do that.
The current instructions build SBCL then pgloader all from sources in a
debian VM. It might be a good idea to maintain a debian+SBCL docker
image and build pgloader on top of that.
