Add more required cgroup subsystems to check-config.sh (specifically, SCHED for cpu and CPUACCT for cpuacct)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Fix a few issues.

-single-dash => --double-dash for a few flags, and also there was a missing "B", as in "Container B".

Docker-DCO-1.1-Signed-off-by: Nathan LeClaire <nathan.leclaire@gmail.com> (github: nathanleclaire)
Merge pull request #6012 from tianon/check-config-cgroup-subsystems

Add more required cgroup subsystems to check-config.sh
Merge pull request #5952 from nathanleclaire/patch-2

Fix a few issues.
Add ability to pause/unpause containers via cgroups freeze

This patch adds pause/unpause to the command line, api and drivers
for use on containers.  This is implemented using the cgroups/freeze
utility in libcontainer.

Co-Authored-By: Eric Windisch <ewindisch@docker.com>
Co-Authored-By: Chris Alfonso <calfonso@redhat.com>
Signed-off-by: Ian Main <imain@redhat.com>