improve xvfb scripts
diff --git a/releng.control/xvfb-restart.sh b/releng.control/xvfb-restart.sh
new file mode 100644
index 0000000..db83a6c
--- /dev/null
+++ b/releng.control/xvfb-restart.sh
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+./xvfb-stop.sh
+
+./xvfb-start.sh