Modify sbast logic to continue when slurmd daemon restarts

Previously a file transmission in progress would be aborted when
any of the slurmd daemons restarted. Now it reconnects, revalidates
the credential, and resumes file transmission.

midplane having a bad nodeboard previously used for passthrough when
the same midplanes were used in a block with a torus connection in that
dim.

Conflicts:
	src/srun/srun.c

allocation.

NOTE: If you were setting the environment variable SLURMSTEPD_OOM_ADJ=-17,
it should be set to -1000 for Linux 2.6.36 kernel or later.

Send signal to srun and let aprun (like poe) forward the signals
rather than sending signal directly to the slurmd and tasks (not
applicable for aprun).

Conflicts:
	src/srun/libsrun/opt.c

and perhaps someone might find it useful).