library: changes to some numa stuff in that <stat> api

library: changes to some numa stuff in that <stat> api

Now that we may be getting serious with documentation,
that stat module was revisited with an eye toward user
friendliness. Heck, even this author puzzled over some
of the existing notes and naming conventions employed.

So, this patch will adjust some identifiers and expand
the notes to (hopefully) better serve potential users.

The most significant change was making the STAT_TIC_ID
always valid for numa nodes, even if any are inactive.

Thus the -22222 special STAT_NODE_INVALID constant now
is applied only to STAT_TIC_NUMA_NODE. It will be used
on the cpu summary and reaps with STAT_REAP_CPUS_ONLY.
And it will also mark any numa node that was inactive.

Signed-off-by: Jim Warner <james.warner@comcast.net>