Added new RPC: SRUN_JOB_COMPLETE.

src/common/slurm_protocol_defs.c

src/common/slurm_protocol_defs.h

src/common/slurm_protocol_pack.c

src/salloc/msg.c

src/slurmctld/agent.c

src/slurmctld/job_mgr.c

src/slurmctld/srun_comm.c

src/slurmctld/srun_comm.h

src/srun/allocate.c

src/srun/msg.c