Fix for record job state on successful allocation but failed reply message.

On a job [pack]allocation RPC request, if the allocation succeed but the
send response message back to the client failed (i.e. srun was killed before
it could receive the response), then modify the job_record pointer so that
the job_state is set to FAILED, the exit_code as if the job got a SIGTERM
signal and the state_reason to FAIL_LAUNCH. Then users when querying
the job with sacct can discern that something bad happend for this scenario,
instead of STATE being showed as COMPLETED and the ExitCode as 0:0.

Bug 4513.