net: disable another external network test
net: disable another external network test

I don't know enough about multicast.
Should this be disabled on all systems, not just Windows?

R=golang-dev
CC=golang-dev
http://codereview.appspot.com/5754060

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