This is a test/example for a nice Make based build system.

The Config.mak should not be saved to the repositories usually, but in this
case it is because part of this demonstration is to show how to customize the
build system through Config.mak, and specially to show how a project can be
"embedded" into another tweaking the Config.mak.

lib1 is a standalone C library compiled into a shared object.  lib2 is another
shared library which uses lib1 and subproj, which is a standalone project
"embedded" into this one. subproj produces another standalone shared object.
Finally, prog is a program which uses lib1 and lib2.

Every project have it's copy of Lib.mak and it's own Toplevel.mak, which has
some global permanent configuration (which doesn't depends on users taste, it
just have information about the project, like it's name, and does the work to
include Lib.mak, etc.). Lib.mak shouldn't be modified ever (unless you're
hacking the build system) and Toplevel.mak should be changes very rarely.

Then each directory containing some library or program to build (or directories
to include) has a Build.mak, which has only the logic to build the
programs/libraries. A well-known Makefile is added to each directory where you
want to be able to do "make", just for convenience. This Makefile should be
created once, with the default target to build and path to the top-level
directory and never touched again. Build.mak should be changes only to add new
programs or libraries to build.