alsa: return EOF from alsa.Read so that pauses can be detected and input stopped

device/alsa/alsa.go

@@ -435,8 +435,8 @@ func (d *ALSA) Read(p []byte) (int, error) {
 	if err != nil {
 		switch err {
 		case nil, io.EOF:
-			d.l.Log(logger.Debug, pkg+"EOF")
-			return n, nil
+			d.l.Log(logger.Debug, pkg+"EOF from Read, stopping")
+			return n, err
 		default:
 			d.l.Log(logger.Error, pkg+"unexpected error from Read", "error", err.Error())
 			return n, nil