CodeQL: apply recommendations

[jessie-murray]

This commit corrects some of the warnings reported by CodeQL: https://lgtm.com/projects/g/nicolasff/webdis/?mode=list

• Use localtime_r instead of localtime
• Use correct argument type in callback to msgpack_packer_new
• Address FIXME in conf.c
• Remove redundant check in websocket.c

I didn't update the source files that come from third-party dependencies like jansson and hiredis, maybe it makes more sense to update them to more recent versions?

[nicolasff]

Hi Jesse!

Thanks for another PR! I'll go over it shortly. I assume you saw my recent attempts at enabling CodeQL through GitHub actions. I just couldn't get it to work, I even used Act to run GitHub Actions locally and had similar issues: CodeQL would just fail to start and not give any error message or indication of what went wrong. I went through all of the docs, tried all the different options to run it, but it never even made any progress so I think I'll give up on it for now.

Yours still look like valuable changes to include.

As for your question about dependencies, I was wondering about these recently since they haven't been touched in years. I remember that there are quite a few warnings coming from hiredis, so that might be a good one to try to update first. I used to work on phpredis with one of the guys who now maintains both, so I could reach out to him if there are still issues.

Thanks again, and I'll make sure this doesn't stay open for long.