[CMake] Clarification around "target_link_libraries"

[SF Markus Elfring]

> Sorry, I don't really understand your question. What generated file names, and 
> what external sources ?

I mean with an external source here a directory which is not directly managed
and controlled by the build system. I see installation directories as a
well-known example for the use case when you occasionally compare the run time
behaviour of an installed library to a freshly built one.
The build system encapsulates file name conventions (and file formats) for the
software generation. I would like to reuse such knowledge so that I can also
refer to libraries from other sources in a generic way.


> Or, since you are it seems mixing C and C++, you have a problem with symbol naming.

Thanks for your hint.

I'm sorry that I overlooked an other preprocessor symbol which is relevant here.
My evolving CMake scripts show better results now.

Regards,
Markus