runtime: fix potential deadlock in netpoll on windows If netpoll has been told to block, it must not return with nil, otherwise scheduler assumes that netpoll is disabled.
runtime: fix potential deadlock in netpoll on windows
If netpoll has been told to block, it must not return with nil,
otherwise scheduler assumes that netpoll is disabled.

R=golang-dev, alex.brainman
CC=golang-dev
https://codereview.appspot.com/11920044

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang