New register allocator branch created

[dewar@gnat.com]

<<I actually find it odd that we do so badly in examples like that.
It makes me wonder if we do the same thing for C++ code. If we do, and
it's spilling link registers like that, all the time, it must *really*
kill virtual function performance, among other things.
>>

Indeed, one has to react partly that the new allocator looks good, but
partly also that the old one seems surprisingly bad in this case.