This should be avoided, but if there are multiple slurm_opt_t entries for
a given val (e.g., -W in sbatch vs srun) check that we've found the correct
entry.

Non-single-character options do not have this issue since they should just
use differing LONG_OPT values.

A number of validation routines - especially within srun -
care whether the variable was set through the environment, or by
an explicit CLI option (or embedded in a job script).

Provide an easy central test so this can be handled for all arguments.

The envvar interface requires some translation to be handled
in the same manner of options returned from getopt_long(),
as it will intentionally return empty strings for certain
variable types.

Match OPT_BOOL processing for flags (defined as has_arg = 0 for
their getopt_long equivalents).

Options will only be printed if set going forward, rather than the
somewhat-arbitrary list of options that we've remembered to add here.

Print each option alongside the value set by slurm_process_option().

Used to create trivial set functions when the argument value is simply
xstrdup()'d into the associated field in slurm_opt_t.

After 426abc7f no jobs should be able to be removed from the
job_list while backfilling is running.

Bug 6621

Timestamps were previously being updated before acquiring mutexes.
Change it to update timestamps after mutexes have been acquired.

Bug 6621

Bug 6621.

purge_old_job() doesn't ever read or write partition info, so remove the
requirement for the partition read lock.

Bug 6621

The backfill scheduler keeps a local list of job pointers. Since the
backfill scheduler yields locks, it's possible for pending jobs to be
canceled and purged in these yield periods. The backfill scheduler then
has pointers to now invalid memory, and dereferencing those pointers is
undefined behavior and may result in a segfault.

This commit prevents purging jobs while the backfill scheduler is
running.

Bug 6621

The next patch will use slurmctld_diag_stats.bf_active to determine
if we can purge jobs or not.

Bug 6621

# Conflicts:
#	src/common/gres.c

Bug 6739

Bug 6803

Bug 6785.