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.

Rather than pack cgroup.conf into a buffer every time we create a new
slurmstepd, pack it once on init and re-use the buffer each time we
create a new slurmstepd. Continuation of 11f70aa5.

Bug 5667

Refactor how memory allocations are managed to accurately track
memory allocations on each node when the --mem-per-cpu option is
used and the CPU count per node varies. Also accounts for
Memory Specialization and wraps much of the logging with
a DebugFlag of SelectType

bug 5562

Update slurm.spec and slurm.spec-legacy as well.