ORDER_BOMB / EXPORT_BOMB status?

[Mark S. Miller <vlad!mark>]

Inspection of the code for these in bombx.hxx seems to be right,
however the comments indicate that its an only-future-tense feature.
With anyone else (including myself), I'd just assume the comments were
out of date, but in this case I thought I'd better check.

Btw, "static class ...." doesn't mean anything in ARM C++.  I don't
know that it ever meant anything in any C++.  (Yes, I know what it
should mean, but I didn't design it)

If ORDER_BOMB & EXPORT_BOMB now work, I think we should consider
DESIGN_BOMB to be obsolete (but left in for now).