with a table that is malloced with 'maxJobs' entries.
Add a 'job_state' field to the Job type that exactly follows which of
the old lists the job was on (or not).
Change all the code that scanned the lists to scan the array.
No logic changes in this commit.
(Soon we'll no longer need to lock out signals for the changes to job
statuses that are done from signal handlers now that there is no linked list.)
11d35f72b2