AM33: adding some more register classes

[Jeffrey A Law]

  In message < orsnw977uf.fsf@zecarneiro.lsd.ic.unicamp.br >you write:
  > --=-=-=
  > 
  > I won't pretend to be able to explain why adding the classes AM33_REGS
  > and SP_OR_AM33_REGS makes any difference, given that they're just
  > duplicates of GENERAL_REGS and ALL_REGS, but the fact is that they do
  > :-)
You should investigate why -- this doesn't make any sense at all.  The way
to do this is to find a function which compiles differently, then look at
the debugging dumps before/after your change to see how they differ.

jeff