Disable script debugging

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/scripts/check-signed-off-by.sh b/scripts/check-signed-off-by.sh
index aaf40a5..4738e37 100755
--- a/scripts/check-signed-off-by.sh
+++ b/scripts/check-signed-off-by.sh
@@ -1,4 +1,4 @@
-#!/bin/bash -x
+#!/bin/bash
 
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.