i960 config

[Neal Becker]

I believe the i960 config for gcc is incorrect.  The various
processors are not compatible, so the multilib support needs to be
expanded.  Right now it only chooses between mnumeric/msoft-float.

I believe it should be more like:

MULTILIB_OPTIONS=mka/mkb/mca
MULTILIB_DIRNAMES=

There could be some more choices as well, but be careful!  gcc
recognizes more choices than gas supports (cs for example is supported 
by egcs but not by binutils-2.8.1.0.18/gas).

Each model processor apparantly uniquely specifies whether or not
floating point hw is present.  So unlike some other families e.g.,
68k, we don't want to build with:

MULTILIB_OPTIONS=mnumerics/msoft-float mka/mkb/mca

What I'm not sure is how to get floating point correct.  Is the first
choice I showed above going to be correct?  Or is it necessary to
explicitly add something to switch between mnumerics/msoft-float as we 
switch cpu options?