This fixes a bug where a system is enforcing memory limits and
the job already has a step running on some of the nodes then
tries to start another step using some of those nodes. For example
wwith DefMemPerNode configured and the select plugin enforcing
memory limits, try:
salloc -N2 bash
$ srun -N1 sleep 10&
$ srun -N2 hostname
Without this patch, the second srun would fail instead of pend.

Conflicts:
	doc/man/man5/cgroup.conf.5
	src/plugins/task/cgroup/task_cgroup_memory.c

use mem and memsw failcnt, check for existence

Thanks Ryan.  I'll let you know how it goes.

info about cgroups on Debian, et al

environment.

task/cgroup: notify if memory.memsw.failcnt > 0. indicates oom

Thanks Ryan, this looks correct.

a common structure instead of multiple parameters to the function.

Hopefully this makes adding new options easier.

Conflicts:
	doc/man/man5/slurmdbd.conf.5