Thread logic needs to allow multiple runs

[jimbair]

When running two runs (say c8s and c9s) at the same time, the following loop logic bleeds between the two runs:

https://github.com/rpminspect/rpminspect-tag-runner/blob/main/tag_runner.sh#L130

I suspect we can do something clever to allow this without it being too convoluted.

[jimbair]

This also runs into stuck builds; if we run into a bug where a build stalls out and you kill the script, the subsequent run will run work until the end of inspections, then it waits for the stuck inspection still. I ran into this with a stuck comparison build on el9 but when I started an el8 run, it got stuck at the end of inspections but before the comparisons.

This would also solve that issue (and we probably should have a trap() to pkill runs as well.