Another batch of PVS Studio fixes

[FeralChild64]

• fixed 30 more warnings
• regarding loguru changes - it seems the project is still being developed (like few commits per year), so once this gets merged I intend to create a GitHub Issue in the loguru project

[kcgen]

The loguru author hasn't given enough people rights to keep the project actively maintained, so it's gotten in a bad state with lots of forks.

Their own master branch fails in their own CI, and they haven't even accepted PRs to get it passing (the only green PRs in their queue include the fix to get their CI working again).

I've got queued PRs that fix real issues, like:

• Add support for Haiku, a POSIX platform without thread naming and vasprintf emilk/loguru#188

And sanitizer cleanups:

• Cleanup static analyzer issues emilk/loguru#179

Back when we adopted it, I forked the project here: https://github.com/dosbox-staging/loguru, and then applied the above fixes to both our fork and the upstream (via PRs, which are stills stagnant).

Currently our fork is still ahead by ~35 commits (and you can see 245 people have launched new forks from ours!):

emilk/loguru@master...dosbox-staging:loguru:master

There are 25 other commits we haven't pulled in versus upstream because they add more warnings or static analysis problems.

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So I would suggest PRing your good Loguru fixes against both Staging loguru and upstream's Loguru. I've added you as admin to the Loguru project here, so you can simply clone, commit, and push.

Once Staging org's Loguru has your fixed commits, then simply copy that new source .cpp/.hpp file into Staging's repo as a single commit "Sync loguru with upstream".

If the upstream loguru does accept your PR at some point, then we just have to rebase against upstream here, and we can continue to keep our loguru project in-sync with little effort.

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The seems convoluted (and it /is/ a bit more work), but the benefit is that we can easily keep our fork of rebased against upstream, if/when it gets updated.

If the loguru commit goes directly into Staging here, then we have divergent code trees versus the upstream projects (both the Staging-loguru repo and it's parent loguru repo).

[weirddan455]

These all look like good low risk changes. I like seeing those warnings continue to get lower. Nice job.

[kcgen]

Very nice cleanup, @FeralChild64.
Was able to review all the commits; looks good to me.