Better integration of third party libraries

[JoGei]

Third party integration in ETISS is a bit intransparent. A lot of libraries are copy-pasted into ETISS source code which is mostly fine, but makes is harder to maintain and differ what foreign code is used (e.g., versioning, missing copyrights/licenses). A few examples, I am aware of:

• pugixml - used in fault injection
• legacy softfloat - kind of anyway a duplicate for the src/jitlib/softfloat
• simpleini - extensive use in ETISS runtime configuration
• tcc - fetched via CMake execute_process

A possible solution to this could be to add a third_party/ directory to ETISS' root to integrate such things - either through git submodules or CMake's FetchContent. Please feel free to extend the list above, if you are aware of more.

[wysiwyng]

I would possibly add tcc to this list, currently it is downloaded and built using CMake's execute_process interfaces, which is arguably not "the best way to do it"™. I have no idea how this could be made nicer, though.

[JoGei]

simpleini fixed with f53752f

[JoGei]

tcc fixed with #125

[wysiwyng]

As far as I see it, the mentioned softfloat is only used for the OR1K core, which probably can be deprecated anyways.

[JoGei]

Agree, but then we should remove OR1K Arch, too.

[JoGei]

pugixml: would be fixed with merge of #132

[JoGei]

Opened a Draft PR: #132