Fixed libcgroup to be aware of hierarchies mounted multiple times.

Fixed libcgroup to be aware of hierarchies mounted multiple times.

Current libcgroup design handles each hierarchy only once. If a hierarchy
is mounted twice or more times, only the first mount point is taken into
account and the others are 'invisible' to libcgroup.

This causes cgsnapshot and lssubsys to show only one mount point for a
hierarchy and especially in case of cgsnapshot it's not what user expects.
The patch below adds a list of all mount points to cg_mount_table_s structure.

Signed-off-by: Jan Safranek <jsafrane@redhat.com>
Acked-by: Ivana Hutarova Varekova<varekova@redhat.com>