proposed patch to improve seperation between kernel and userland code

[Matthew Dillon]

:The attached patch probably deserves some discussion, so I'm posting it
:here first rather than straight to the submit list.
:
:The idea is to enhance the distinction between kernel source code and
:userland source code.  (This started as sort of an offshoot of removing
:parameter names from function protoypes in userland-accessible headers.)

     * libdisk should probably still be made part of the build.

     * I'm on the fence in regards to sys/dir.h.  If it is possible I
       would prefer that it be left working.

     Generally speaking, the stuff looks pretty good.  I think it is
     commitable with the above two changes, with the provisio that we
     may have to revert additional pieces of it if we start getting
     complaints about ports.

						-Matt