It seems to me that the `device-driver' and `config-dependent' flags
are antiquated, and should probably be removed.

There's only one thing in the `PARAM' variable these days: the
definition of `MAXUSERS'.  I find it hard to believe that there's any
reason not to just stick this in `IDENT' instead.  One might argue
that things used only by param.c should go in `PARAM', but there are
many things used by param.c that don't go there.  (In fact, `MAXUSERS'
is just a strange special case.)

There's only one use of `config-dependent' (and thus only one other
use of `PARAM') -- for the mvme68k machdep.c.  This appears to be
gratuitous.

As for `device-driver', I believe that was originally used to compile
device drivers differently so that register accesses would work in a
predictable fashion.  It's actually not possible to do this with GCC
any more, and we now use `volatile' and special-purpose register
access functions like the bus_*() macros instead to get guaranteed
behaviour.

So, in short, I believe these flags should simply be removed, and the
Makefiles updated accordingly.

Comments?