Apply read and write deadlines to pending IO

In order to upgrade to go1.8 all IO operations
including previous pending IO must have the deadline
set when SetReadDeadline or SetWriteDeadline is called

Signed-off-by: Darren Stahl <darst@microsoft.com>

pipe.go

@@ -367,7 +367,7 @@ func connectPipe(p *win32File) error {
 		return err
 	}
 	err = connectNamedPipe(p.handle, &c.o)
-	_, err = p.asyncIo(c, time.Time{}, 0, err)
+	_, err = p.asyncIo(c, nil, 0, err)
 	if err != nil && err != cERROR_PIPE_CONNECTED {
 		return err
 	}