cmd/dist: generate cmd/cgo/zdefaultcc.go on windows (fixes windows build)
cmd/dist: generate cmd/cgo/zdefaultcc.go on windows (fixes windows build)

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/12404043

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