Fix job cleanup even if there is no more job.
Fix job cleanup even if there is no more job.

Until now, finished jobs were only removed from the ui and from the
running_jobs list if we expected to have a next job. However, if
we only started a reduce job then it got stuck on the screen even
after finishing. The patch fixes this.

renatahodovan/fuzzinator,renatahodovan/fuzzinator,akosthekiss/fuzzinator,renatahodovan/fuzzinator,akosthekiss/fuzzinator,renatahodovan/fuzzinator,akosthekiss/fuzzinator,akosthekiss/fuzzinator