1. X86 fixes/changes

   a.  x86Rewrite bug with MUL3 (found by Lal)
   b.  Added the instructions FSTS, FSTL

2. PA-RISC fixes/changes

   a.  B label should not be a delay slot candidate!  Why did this work?
   b.  ADDT(32, REG(32, r), LI n) now generates one instruction instead of two,
       as it should be.
   c.  The assembly syntax for fstds and fstdd was wrong.
   d.  Added the composite instruction COMICLR/LDO, which is the immediate
       operand variant of COMCLR/LDO.

3. Generic MLRISC

   a.  shuffle.sml rewritten to be slightly more efficient
   b.  DIV bug in mltree-simplify fixed (found by Fermin)

4. Register Allocator

   a.  I now release the interference graph earlier during spilling.
       May improve memory usage.