It was left in netFD.connect() by an oversight (as the name
implies, bind has no business being in connect). As a result
of this change and by only calling netFD.connect() when ra
isn't nil it becomes simpler with less code duplication.

Additionally, if netFD.connect() fails, set sysfd to -1 to
avoid finalizers (e.g. on windows) calling shutdown on a
closed and possibly reopened socket that just happened to
share the same descriptor.

R=golang-dev, rsc1, rsc
CC=golang-dev
https://golang.org/cl/4328043