utils: add janus_strlcat helper

[tmatth]

This will log an error if the output is truncated.

[tmatth]

N.B. this can take a backseat to #2793 (I'll rebase it after that gets merged) but I think would be useful for the rest of the codebase.

[lminiero]

I think it makes sense to merge yours first (in order to check when truncation is indeed the cause of the issue), and then expand it with @JanFellner's patch to make it extend the buffer rather than fail (and maybe print the error you have now in case the reallocation fails, for instance).

[JanFellner]

Works now on my side. So the buffer size was really the issue.

[tmatth]

I think it makes sense to merge yours first (in order to check when truncation is indeed the cause of the issue), and then expand it with @JanFellner's patch to make it extend the buffer rather than fail (and maybe print the error you have now in case the reallocation fails, for instance).

Sure just wanted to make sure I wasn't scooping @JanFellner's work but this should be a lower impact/risk change.

[lminiero]

Apart from a tiny code-style nit (I know, I'm the worst 😆 ), this looks like a good fence to me. I already know it will cause me more than a little headache when re-aligning multistream (it will likely cause many conflicts), but that's indeed needed. I'll make a couple of tests, then merge and address the multistream conflicts so that we can start addressing the SDP size there.

[lminiero]

Thanks for the quick fix! Merging then, and heading down the multistream merge conflicts hole...