Precompiled default interlocker and train libraries do not work on (Linux) x86_64

[BLuedtke]

When startup is called for a running swtbahn-cli server, the default interlocker libraries and the default train-engine libraries are loaded dynamically. The lib files are located at server/src/interlockers and server/src/engines respectively (.so and .dylib files).

These shared libraries were compiled on a particular device at some point. Not sure exactly where/how. Regardless, the current precompiled libraries can't be loaded when running the swtbahn-cli server on an x86_64 linux device (in this case, running Kubuntu 22.04 with kernel 5.15.0-46). Loading them results in header/ELX (ELF?) conflicts, which is not particularly suprising, assuming that they were compiled on a different architecture and with a different kernel.

To be able to run the swtbahn-cli server on an x86_64 linux device, one has to re-compile new default engines and interlockers, and place them in the appropriate locations. Whilst that is technically possible, there is no source file for the default train engines, at least not in this repository. For the interlockers, there are two source files which can be used.

I see multiple possible solutions:

• Supply the source for default train engines and re-compile them on demand upon startup, should loading the default libraries fail
• Supply additional precompiled libraries explicitly for x86_64, that are loaded if loading the standard loading fails (or, smarter: use preprocessor to directly load the appropriate libraries).

Any changes to the handling of these libraries must be tested on Mac/Apple as well; if possible also with newer ARM based Macs.

Note: This is not a high-priority issue.