sched/wiki2 - Correct CPU load reported to Moab

I'm running Slurm 2.6.0 and MWM 7.2.4 in our test cluster at the moment.  I happened to notice that node load reporting wasn't consistent- periodically you'd see a "sane" load reported in Moab, but most of the time the reported load was zero despite an accurate CPULoad value reported by "scontrol show node".

Finally got to digging into this.  It appears that the only time load was being reported properly was in the Moab scheduling cycle directly after slurmctld did a node ping.  In subsequent scheduling cycles the load (again, as reported by Moab) was back to zero.

The node ping is significant as that is the only time the node is updated- since the wiki2 interface only reports records that change, and the load record isn't changed, it isn't reported in the queries after the node ping.

Judging from this behavior, I'm guessing that Moab does not store the load value- every time it queries resources in Slurm it sets the node's load back to zero.

I've altered src/plugins/sched/wiki2/get_nodes.c slightly- basically moved the section that reports CPULOAD above the check for updated info (update_time > last_node_update).

So I don't know if this is the appropriate way to fix it.  The wiki specification that Adaptive has published doesn't seem to indicate how this should function.  Either MWM should assume the last value reported is still accurate or Slurm needs to report it for every wiki GETNODES command.

Anyway, the patch is attached, it seems to be working for me, and I've rolled it into our debian build directory.  YMMV.

Michael