Reverts most of commit 84023f27.

Searching the PATH in slurmd can fail due to root_squash'd NFS
filesystems, leading to the "wrong" program being launched.

If you'd like the performance benefit from avoiding this lookup
during each separate task launch, set SLURM_TEST_EXEC=1 instead
which will perform the lookup once within srun, which then ensures
the lookup happens under the users own environment and not that
of the slurmd.

Bug 2992.

level.

Provide limited support for the MemSpecLimit configuration parameter without
    the task/cgroup plugin.

If the second call to getgrouplist() found additional groups,
ngroups will be overwritten with this new larger value, while
the gids list would be truncated. (ngroups is a value-result arg.)
This will then lead to _gids_cache_lookup() returning the wrong
number of groups including invalid parts of memory, which are likely
to include some zeros.

Those zeros could then make it to the setgroups() call and thus
give the user access to the root group. Especially as setgroups
will succeed as long as the array does not contain -1 as a gid.

Bug 3320.

task/cgroup - Change error message if CPU binding can not take place to
    better identify the root cause of the problem. Specifically, if
    the hwloc_get_obj_below_by_type() function call completely fails
    that is likely due to task/affinity not being configured, so
    cpusets are not configured. Previous message was
    "task/cgroup: task[%u] infinite loop broken while trying to provision compute elements using %s (bitmap:%s)"
    The new message is
    "task/cgroup: hwloc_get_obj_below_by_type() failing, task/affinity plugin also required"

uint32_t needs %u on 32-bit platforms. Noticed by clang/travisci.

Bug 3258

This reverts commit 817c2ca4.

# Conflicts:
#	NEWS

a slurmctld restart or reconfig, as they aren't really error messages.

Bug 3258

Bug 3258

Done jost to run "git push" again after internal github error on
  previous push:
remote: Resolving deltas: 100% (4/4), completed with 4 local objects.
remote: Unexpected system error after push was received.
remote: These changes may not be reflected on github.com!
remote: Your unique error code: bdecb7b0f321368fe1f037a81a6e9c2c

Note that this does not protect against all possible problems here.
The setgroups() call in Linux at least is willing to set any gid_t
value except -1 on a group, so calls will not always fail on corrupted
group lists.

Bug 3320.

Remove uncached _get_grouplist() call which was only used here.

Bug 3315.

Fix parsing in regression test1.92 for some prompts.
bug 2792

Recognize a KNL's proper NUMA count (rather than setting it to the value
    in slurm.conf) when using FastSchedule=0. Previous logic would change
    the NUMA count on the node to match what was in slurm.conf, which would
    mess up task layout with respect to the sockets.
bug 3306

from the slurm.conf when using FastSchedule=0.

cray/burst_buffer - If slurmctld daemon restarts with pending job and burst
    buffer having unknown file stage-in status, teardown the buffer, defer the
    job, and start stage-in over again.
bug 3295

bug 3314

Add support for SALLOC_CONSTRAINT, SBATCH_CONSTRAINT and SLURM_CONSTRAINT
    environment variables to set default constraints for salloc, sbatch and
    srun commands respectively.
Bug 3317

limits after the node selection to make sure it doesn't violate those limits
and if it does change the reason for waiting so we don't reserve resources
on jobs violating accounting limits.

Bug 3029

node_features/knl_cray - Fix possible race condition when changing node
    state that could result in old KNL mode as an active features.
bug 3235

cray/burst_buffer - Increase time to synchronize operations between threads
    from 5 to 60 seconds ("setup" operation time observed over 17 seconds).
    This should fix a race condition between a thread performing a buffer
    creation (setup) and a thread looking for unexpected buffers. If a
    buffer is found during the time window allowed for creation, it's
    space will be counted twice. First by the status checking thread
    and second by the thread doing the creation. The deallocation only
    happens once, so the used space information can be left with an
    invalid value.
bug 3295

static variable means multiple active decompression streams will corrupt
zlib's internal state, which can lead to a segfault.

Bug 3299.

On a reconfig, the exc_node_bitmap is cleared but then it was
not built again since last_work_scan was declared as a local static
variable in _do_power_work(). The fix is to make it global within the
plugin and reinitialize it to 0 on _init_power_config().

Bug 3078.

For example:
     Nodes=nid00001 CPU_IDs=2-3 Mem=1000 GRES_IDX=gpu:alpha(IDX:2)
     Nodes=nid00002 CPU_IDs=0-1 Mem=1000 GRES_IDX=gpu:alpha(IDX:0)

Bug 3291.

If GRES are configured with file IDs, then "scontrol -d show node" will
    not only identify the count of currently allocated GRES, but their specific
    index numbers (e.g. "GresUsed=gpu:alpha:2(IDX:0,2),gpu:beta:0(IDX:N/A)").

Bug 3267.

Termination can race against step creation if, e.g., ill-behaved SPANK plugins
are in use.

Bug 3248.

Added SchedulingParameters option of "bf_job_part_count_reserve". Jobs below
    the specified threshold will not have resources reserved for them.
bug 3275

messages.  Hopefully this will reduce the number of messages lost when
filling up memory when the database/DBD is down.

sched/backfill plugin: Make malloc match data type (defined as uint32_t and
    allocated as int). No failures observed, if type "int" is smaller than
    "uint32_t", it could result in an invalid memory reference.

Fix API call: slurm_job_cpus_allocated_str_on_node_id() and
in turn slurm_job_cpus_allocated_str_on_node() to return correct
results for anything but first node. This was caused by missed logic
to calculate fist bit belongs to particular node. Lookup was always
starting from bit 0.

Bug 3266.