io: Don't call close multiple times in QIOChannelFile

If the file descriptor underlying QIOChannelFile is closed in the
io_close() method, don't close it again in the finalize() method since
the file descriptor number may have been reused in the meantime.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

io/channel-file.c

@@ -178,6 +178,7 @@ static int qio_channel_file_close(QIOChannel *ioc,
                          "Unable to close file");
         return -1;
     }
+    fioc->fd = -1;
     return 0;
 }