runtime: fix false positive deadlock when using runtime.Goexit Fixes issue 4893. Actually it's fixed by cl/7314062 (improved scheduler), just submitting the test.
runtime: fix false positive deadlock when using runtime.Goexit
Fixes issue 4893.
Actually it's fixed by cl/7314062 (improved scheduler),
just submitting the test.

R=golang-dev, rsc
CC=golang-dev
https://codereview.appspot.com/7422054

d0f/go-zh,mhennings/marcohennings-go,rdp/rogerpack2005-golang,d0f/go-zh,sanjosh/sanjos100-tipc,scirelli/scirelli-go,mhennings/marcohennings-go,sanjosh/sanjos100-tipc,bryanxu/go-zh,rdp/rogerpack2005-golang,mhennings/marcohennings-go,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,scirelli/scirelli-go,rdp/rogerpack2005-golang,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,sanjosh/sanjos100-tipc,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,sanjosh/sanjos100-tipc,scirelli/scirelli-go,rdp/rogerpack2005-golang,bryanxu/go-zh,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,d0f/go-zh,scirelli/scirelli-go,bryanxu/go-zh,webfd/go-zh,d0f/go-zh,scirelli/scirelli-go,bryanxu/go-zh,mhennings/marcohennings-go,rdp/rogerpack2005-golang,scirelli/scirelli-go,bryanxu/go-zh,mhennings/marcohennings-go,bryanxu/go-zh,webfd/go-zh,d0f/go-zh,mhennings/marcohennings-go,bryanxu/go-zh,webfd/go-zh,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,d0f/go-zh,mhennings/marcohennings-go,bryanxu/go-zh,scirelli/scirelli-go,sanjosh/sanjos100-tipc,sanjosh/sanjos100-tipc,webfd/go-zh,scirelli/scirelli-go,rdp/rogerpack2005-golang,mhennings/marcohennings-go,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,d0f/go-zh,glycerine/jeaten-go-arrayof-structof