[RFA]: gdbserver cleanup, add m68k & ns32k support to low-nbsd.c

[Stan Shebs]

"J.T. Conklin" wrote:
> 
> I submit the enclosed patch for approval.
> 
> I only planning to add support for m68k and ns32k based NetBSD
> systems, when I found some unused variables, etc. in the low-*.c
> files.  I couldn't fix the instances in only low-nbsd.c without
> fixing the others, so those changes are in here as well.

These are fine with me.  (It would be nice to share the fetch/store
functions with GDB proper, but that's a little more complicated
to make happen!)

Stan