This sets more per-pack-job environment variables for launched steps.
All of the following are used by Open MPI:
SLURM_CPUS_PER_TASK
SLURM_STEP_NUM_TASKS
SLURM_TASKS_PER_NODE
A few more env vars are still needed by OpenMPI

Without this patch, the default name of all pack job components
  submitted by salloc was "sh"

These are required by OpenMPI

Commit c125875f introduced a
  change that with some compilers generates a warning about the
  "const" variable definition being ignored on an assignment.

Modify output of "--mpi=list" to avoid duplicates for version numbers in
    mpi/pmix plugin names.

Notify user if he tries to start a job step with a higher pack group
  value than the number available in the job allocation. Previous
  logic would abort the srun.

Modify sbcast command and srun's --bcast option to support heterogeneous
      jobs.
bug 4099

This should have been addressed in earlier commit, but was not noticed
  until trying to build on cluster with nrt software

Make sure no vestigial jobs are left after the test

In srun, if only some steps are allocated and one step allocation fails,
 then delete all allocated steps.

Set SLURM_NTASKS environment variable to reflect global task count
(needed by MPI).

Set SLURM_PROCID environment variable to reflect global task rank
(needed by MPI).

Coverity CID 45205

Coverity CID 44959

Coverity CID 171461

Hoping this clears warning
Coverity CID 171474

Coverity CID 45178

Coverity CID 44722

Coverity CID 44682

Coverity CID 44924

Coverity CID 45205

Coverity CID 44683

Coverity CID 45195

Coverity CID 48904

Coverity CID 166002

Coverity CID 174399

Fix typo
Coverity CID 174400

bug 3217