New register allocator branch created

[Daniel Berlin]

> Ehm, I was trying to build a compiler using the new register allocator,
> but reload complains about not being able to find a register to spill
> while compiling libgcc2.

Also, reload shouldn't be doing spill code register allocation, just spill
code insertion. The new allocator expects to be allocating registers
for temporaries used in spill code, by iterating. I haven't gotten
this going yet.
Once i get that handled, you'll never see that message again.

--Dan