Modular build system

[matheusmoreira]

The build system has the potential to be a reusable framework. It should be split into its own git repository.

• [x] Move all build system framework code out of make/ and into .make/
• [ ] Move all liblinux-specific code out of .make/ and into make/
• [ ] Split the .make/ directory into its own git repository
• [ ] Replace the .make/ directory with a git submodule