go spec: unsafe.Alignof/Offsetof/Sizeof return uintptr
go spec: unsafe.Alignof/Offsetof/Sizeof return uintptr

This is (indirectly) a language change. Per e-mail discussion
on golang-dev.

Fixes issue 1943.

R=rsc, iant, r, ken
CC=golang-dev
http://codereview.appspot.com/4581058

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