preempt/job_prio plugin: Implement the concept of Warm-up Time here. Use
the QoS GraceTime as the amount of time to wait before preempting.
Basically, skip preemption if your time is not up.

Bug 1627

This is a special case. This change documents the way Slurm has
always worked.

Make sure that old step data is purged when a job is requeued.
Without this logic, if a job terminates abnormally then old step
data may be left in slurmctld. If the job is then requeued and
started on a different node, referencing that old job step data
can result in abnormal events. One specific failure mode is if
the job is requeued on a node with a different number of cores,
and the step terminated RPC arrives later, the job and step
bitmaps of allocated cores can differ in size generating an
abort.
bug 1660

Bug 1618

cpu count.

random crashing in db2 when the slurmctld is exiting.

Signed-off-by: Danny Auble <da@schedmd.com>

In slurmctld communication agent, make the thread timeout be the configured
value of MessageTimeout (or 30 seconds, whichever is larger) rather than
30 seconds.