sync/atomic: fix LoadInt32 on ARM R0 is clobbered after cas, while R1 preserves its value.
sync/atomic: fix LoadInt32 on ARM
R0 is clobbered after cas,
while R1 preserves its value.

R=golang-dev
CC=golang-dev
http://codereview.appspot.com/4782042

Committer: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

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