AM33 base and index registers clean-up

[Alexandre Oliva]

On Apr 21, 2000, Alexandre Oliva <aoliva@cygnus.com> wrote:

> This patch allows all AM33 registers to be used as base and index
> registers

Here's the patch.  Actually, it could still be further split.  The
change to the .md file is required if the change to the .h file is
installed, but it might be a good idea to install the .md change even
if the .h doesn't make it.