making the COMPAT_43 option optional

["David P. Reese Jr." <daver@xxxxxxxxxxxx>]

I've managed to build some simple kernels without the COMPAT_43 option
with the help of some strategically placed #if defined()'s.  I'm curious
if we even need this option any more.

By the end of the week I hope to have LINT building without COMPAT_43
and after that I'll try to tackle world.  I'm out of town until the middle
of the week so I won't be able to participate in the should-we-do-it
discussion, but I'd like to hear some kind of consensus by then.

This is the kind of support that we plan on buliding into the userland
emulation layer, right?

-- 
   David P. Reese, Jr.                                     daver@xxxxxxxxxxxx