Fix inaccurate values in /proc/meminfo for containers with child cgroups

Fix inaccurate values in /proc/meminfo for containers with child cgroups

The values for Cached, Active, Inactive, Active(anon), Inactive(anon),
Active(file), Inactive(file), and Unevictable are derived/computed
from these values in the relevant meminfo.stat:

cache
active_anon
inactive_anon
active_file
inactive_file
unevictable

However, these value apply only to the cgroup of the lxc container
itself.  If your container uses memory cgroups internally, and thus
the container cgroup has children, their memory is not counted.

In order to take the memory usage of child cgroups into account, we
need to look at the "total_" prefixed versions of these values.

Signed-off-by: Aaron Sokoloski <asokoloski@gmail.com>