Major clean-up of slurm_protocol_pack (not finished, but about half done).

for mutex lock/unlock with error messages.

slurmctld can set a node down per bad slurmd return code in
job completion RPC.
slurmd has framework for returning both slurmd and and application
return codes on batch job completion.
Srun modified to send return codes on job completion

slurmctld can set a node down per bad slurmd return code in
job completion RPC.
slurmd has framework for returning both slurmd and and application
return codes on batch job completion.

slurmctld can set a node down per bad slurmd return code in
job completion RPC.

   logfile == NULL

   This will allow slurmd to run as non-root process for testing.

 o mgr.c : deallocate job if preparation fails

Initialize return code for batch job initiation.

spooling file.