Only merge levels in lstopo-text when cpuset is equal and arity is 1.
Only merge levels in lstopo-text when cpuset is equal and arity is 1.

It'll help machines with NUMA nodes without CPUs (we want to keep
these even if their cpuset is empty, but we don't want a single
non-empty node to be merged with the machine).

git-svn-id: 14be032f8f42541b1a281b51ae8ea69814daf20e@135 4b44e086-7f34-40ce-a3bd-00e031736276

BlueBrain/hwloc,BlueBrain/hwloc,BlueBrain/hwloc,BlueBrain/hwloc