SPARC: Set up a lookup table for integer register flattening.

SPARC: Set up a lookup table for integer register flattening.
Using a look up table changed the run time of the SPARC_FS solaris boot
regression from:

real    14m45.951s
user    13m57.528s
sys     0m3.452s

to:

real    12m19.777s
user    12m2.685s
sys     0m2.420s