Fix non-blocking SocketChannel connects.

There are many reasons why the initial connect(2) may have resulted
in a ConnectException, only one of which (EINPROGRESS) means we haven't
yet failed.

Bug: https://code.google.com/p/android/issues/detail?id=56684
Change-Id: I2115998bce9043f076418fb0d1c22a26e04ee2e1