Creation of compatible build directory hierarchy from source information

[SF Markus Elfring]

Hello,

I would like to achieve something which is described in following documents.

* An alternative approach to subdirectories
  https://www.gnu.org/software/automake/manual/html_node/Alternative.html

* Non-recursive Automake
  https://autotools.io/automake/nonrecursive.html


I find a specific build dependency unclear at the moment after I constructed two
small files “configure.ac” and “Makefile.am” for my software development needs.
How should (and will) separate output directories be created for an
out-of-source build (VPATH) before a compilation command may try to write
anything there?

Regards,
Markus