Introduce and use a per-CPU read-mostly sub-section

Introduce and use a per-CPU read-mostly sub-section

Since mixing data that only gets setup once and then (perhaps
frequently) gets read by remote CPUs with data that the local CPU may
modify (again, perhaps frequently) still causes undesirable cache
protocol related bus traffic, separate the former class of objects
from the latter.

These objects converted here are just picked based on their write-once
(or write-very-rarely) properties; perhaps some more adjustments may
be desirable subsequently. The primary users of the new sub-section
will result from the next patch.

Signed-off-by: Jan Beulich <jbeulich@novell.com>