deprecating #define'd sysctl OIDs

[Alan Barrett <apb%cequrux.com@localhost>]

On Sun, 15 Aug 2010, Jean-Yves Migeon wrote:
> > It might make sense to add comments near all existing lists of
> > hard-wired sysctl OID values asking people not to add more of them.
> 
> Shall it be added for all other archs then? I assume that they can all
> benefit from the dynamic sysctl(9) interface?

If we do this at all, then we should do it for all lists of sysctl
OID values.  Several of them are in sys/sysctl.h, and I am sure
there are more scattered around.  I don't see the point of doing
it only for CPU_* definitions.

All three of the sysctl(3), sysctl(7), and sysctl(9) man pages
could also be improved, to make it more clear that new code can
(should?) use dynamic allocation instead of #define'd OID values.

--apb (Alan Barrett)