service: don't leak a zero file descriptor

CID 1141017 (#1-2 of 2): Resource leak (RESOURCE_LEAK)
14. leaked_handle: Handle variable fd going out of scope leaks the handle.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

lib/criu.c

@@ -211,7 +211,7 @@ static int send_req_and_recv_resp(CriuReq *req, CriuResp **resp)
 	}
 
 exit:
-	if (fd > 0)
+	if (fd >= 0)
 		close(fd);
 
 	return -ret;