Issue a batch request to checkpoint a batch job.
pbs_checkpointjob() a "Checkpoint Job"
batch request is generated and sent to the server over the connection
which is the return value of pbs_connect().
The server will reply when the job has completed the checkpoint operation.
Checkpointing is only allowed for jobs that are marked as checkpointable.
These requests requires that the issuing user have operator or
identifies which job is to be checkpointed, it is specified in the form:
is reserved for implementation defined extensions.
It is not
currently used by these functions.