Makes it more obvious which files are actually installed. MKINSTALLDIRS
still spurs out a lot of 'mkdir ...', which probably should also be
silenced when V=0.
It is a little ugly since I couldn't get $(wildcard) to expand *.o files
so it just checks if there are any *.c files and then link in the lib.o
based on that.
Ditch the building of an archive (.a) in favour of linking all objects in a
directory into a lib.o file. This makes it easy to link in subdirectories
and more importantly keeps the build logic in the local subdirectories.
Note: after updating you will have to rm **/*.a if you do not make clean
before updating.
Finally, we are able to identify the builds more accurately. Now we check
if commit-id (cogito tool) is available and pass the output to vernum.c
compilation which then exports it as a build_id string.
The first line of --version is now a bit long, we should probably move the
build date to a second indented line or something.
