R_xxx counterparts to the V_xxx macros

[James Gritton]

Julian Elischer wrote:
> It's an interesting idea, however what is the "real" hostname?
> what makes one vimage the 'real' one?

You could ask this if all images were indeed equal.  However, they're 
hierarchical, and there's one that is there when the box starts up, and 
can't be gotten rid of.  If there weren't a "real" hostname, there would 
never be a place in the code where you don't have a better choice than 
using thread0's credential.

> I wouldn't do it for all variables however.. 

Quite true.  I suspect that most variables replaced by vnet always have 
a context that they naturally belong to, and would never need to know 
about a "real" value.  I think it's the few that are outside of vnet 
that would most show this.

My focus right now is jail integration, so these are the parts that I 
notice, as vnet wouldn't be integrated with jails so much as placed on 
top of them (as they are now placed on top of vimage which is almost but 
not quite entirely vnet).

- Jamie