This gets c.config.Spec.Linux.Resources, with some nil checks.
Using this means less open coding of the nil-checks, but also the
existing user of this field in moveConmonToCgroupAndSignal() was
using ctr.Spec().Linux.Resources instead, and the Spec() call
is very expensive.
[NO NEW TESTS NEEDED] Just minor performance effects
Signed-off-by: Alexander Larsson <alexl@redhat.com>