avoid unused variable in front-end mode

Add new node state flag of NODE_STATE_REBOOT for node reboots triggered by
    "scontrol reboot" commands. Previous logic re-used NODE_STATE_MAINT flag,
    which could lead to inconsistencies. Add "ASAP" option to "scontrol reboot"
    command that will drain a node in order to reboot it as soon as possible,
    then return it to service.
bug 3210

bug 3213

select/linear plugin modified to better support heterogeneous clusters when
    topology/none is also configured. Note that use of the select/cons_res
    plugin is strongly recommended for heterogeneous clusters. The use of
    OverSubscribe=exclusive can be used if whole node allocations is
    desired.
bug 3212

Bug 3224.

Different paths were used in various locations. All changed to use
  the /var/spool directory.

If a job is started by the main scheduling logic and requeued while
  the backfill scheduler has locks released, that can result in an
  invalid data structure in select/cons_res. Namely, the backfill
  scheduler's attempt to start the job would clear the job resources
  node_bitmap. That leaves a NULL pointer in the select/cons_res
  plugin generating an abort. (That pointer is needed to clean up
  the job allocation records when the Epilog or Cray Node Health
  Check, NHC, are complete and the resources become available for
  another job.
bug 3230

task and can get quite verbose on a KNL node.

warning fix.

if the pointer is valid

Backup slurmctld will now
1. Not abort due to NULL pointer (needed to move code around on restart)
2. Recover KNL MCDRAM and NUMA modes from state save files if capmc and
   cnselect not available
bug 3241

cray/burst_buffer - Update "instance" parsing to match updated dw_wlm_cli
    output.
bug 3222

No change to logic

cons_res.

requests when they = 1.

What we did was just increase the cpus_per_task to equal the amount of
threads in the core|socket.  This was done with an array to handle
heterogeneous systems.

Bug 2519

Hopefully this will make alterations to this function easier as it doesn't
now consider ntasks_per_*.

Expand the dw_wlm_cli script to include persistent and job-specific
  burst buffers. This script is used by burst_buffer/cray.

Add "FreeSpace" information for each pool to the "scontrol show burstbuffer"
    output. Required changes to the burst_buffer_info_t data structure.
bug 3222

This is a new field and the fix only applies to an emulated burst
  buffer configuration (i.e. dw_wlm_cli script made to look like
  a real DataWarp system)

Change error() to verbose(). New logic is needed to address this issue
   once we know how to determine the KNL MCDRAM size.

cray/burst_buffer - Preserve job ID and don't translate to job array ID
  after slurmctld restart. Prior logic would not set array_task_id to
  NO_VAL, so all job-buffer IDs would be reported in the form
  "JobID=0_0(123)" rather than "JobID=123"

cray/busrt_buffer - Internally track both allocated and unusable space.
    The reported UsedSpace in a pool is now the allocated space (previously was
    unusable space). Base available space on whichever value leaves least free
    space.
bug 3222