pidigits: ~10% performance win by using adds instead of shifts
pidigits: ~10% performance win by using adds instead of shifts

user time for pidigits -s -n=10000:
6.466s w/ adds
7.138s w/ shifts

R=rsc
CC=golang-dev
http://codereview.appspot.com/1021041

glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,sanjosh/sanjos100-tipc,scirelli/scirelli-go,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,d0f/go-zh,mhennings/marcohennings-go,rdp/rogerpack2005-golang,npe9/noahevans-go9,mhennings/marcohennings-go,scirelli/scirelli-go,d0f/go-zh,d0f/go-zh,glycerine/jeaten-go-arrayof-structof,Triskite/willstone-goclone,webfd/go-zh,Triskite/willstone-goclone,rdp/rogerpack2005-golang,Triskite/willstone-goclone,mhennings/marcohennings-go,npe9/noahevans-go9,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,Triskite/willstone-goclone,mhennings/marcohennings-go,bryanxu/go-zh,webfd/go-zh,sanjosh/sanjos100-tipc,webfd/go-zh,npe9/noahevans-go9,webfd/go-zh,rflanagan/reginaldflanagan-project1,d0f/go-zh,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,d0f/go-zh,Triskite/willstone-goclone,scirelli/scirelli-go,Triskite/willstone-goclone,scirelli/scirelli-go,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,bryanxu/go-zh,sanjosh/sanjos100-tipc,scirelli/scirelli-go,npe9/noahevans-go9,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,d0f/go-zh,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,scirelli/scirelli-go,webfd/go-zh,npe9/noahevans-go9,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,mhennings/marcohennings-go,sanjosh/sanjos100-tipc,bryanxu/go-zh,Triskite/willstone-goclone,bryanxu/go-zh,bryanxu/go-zh,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,d0f/go-zh,npe9/noahevans-go9,rdp/rogerpack2005-golang,webfd/go-zh,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,npe9/noahevans-go9,npe9/noahevans-go9,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,rdp/rogerpack2005-golang,rflanagan/reginaldflanagan-project1,rdp/rogerpack2005-golang,mhennings/marcohennings-go