PATCH: add pa2.0 system instructions

[Jeffrey A Law]

  In message < 14214.11878.766249.924457@gargle.gargle.HOWL >you write:
  > But, if we're willing to go to the effort
  > of prefixing to free up codes, we can handle this by adding codes that only
  > accept registers versus the ones that cast immediates to registers.  In
  > this case, the stricter syntax restriction comes for free.
I think it's just as easy (or easier) to require % prefixing for registers
when dealing with new syntax.  That's how HP's assembler works and that's
basically what the FLAG_STRICT stuff does.  Anytime we're trying to match
an opcode using the new syntax we require all register operands to be prefixed
with %.

I've always hated the way HP allowed immediate values to be used in place of a
register or allowed you to simply omit operands (they would be silently
filled in as zero).  This kind of braindamage has led to numerous bugs in
hand-written assembly code over the years.

jeff