syscall: Correct length of SockaddrUnix.
syscall: Correct length of SockaddrUnix.

R=rsc
CC=golang-dev
http://codereview.appspot.com/4025041

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