With jobs launched using srun directly which end abnormally, there will
be a step-killed-message(slurmd[cn123]: *** 1234.0 KILLED AT ... WITH
SIGNAL 9 ***) from each node. And/or there will be a
task-exit-message(srun: error: task[0-1]: Terminated) for each node. For
large scale jobs, these messages become tedious and the other error
messages will be buried. The attached two patches(for slurm-2.5.1)
introduce two environment variables to control the output of such
messages:

SLURM_STEP_KILLED_MSG_NODE_ID: if set, only the specified node will
print the step-killed-message;

SLURM_SRUN_REDUCE_TASK_EXIT_MSG: if set and non-zero, successive task
exit messages with the same exit code will be printed only once.

User root or SlurmUser don't need valid sbcast credential

This can be useful for testing purposes

Used to specify the communication protocol to be used for ALPS/BASIL.