c library does not allow disable debug without changing the code

[ArFe]

The c library defines #define SPARKPLUG_DEBUG 1 in the code.

That prevents anyone from disabling the debug print without changing the code, as DEBUG_PRINT is defined if SPARKPLUG_DEBUG is defined or not. https://github.com/eclipse/tahu/blob/d6552c9f52e96f58b5ca30ccc9d3652861cb0b9c/c/core/include/tahu.h#L31-L38

If you change the code you have to disclose your source code, as per the license, which makes it hard to use it in professional projects.

[wes-johnson]

If you want to resubmit a PR against a Github account where you've signed the ECA, I'm fine to accept this. I also am not a lawyer, but I'm not sure your interpretation of the Eclipse Public License is entirely correct. Regardless, I'll leave this open for a while if you want to resubmit that PR.