iar-docker-images/builders.sh: set -ex for debugging

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: I25557400e6c36e91bb30500299786ab7a9af6f84
diff --git a/iar-docker-images/builders.sh b/iar-docker-images/builders.sh
index 65250ae..67a5861 100755
--- a/iar-docker-images/builders.sh
+++ b/iar-docker-images/builders.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -ex
+
 docker --version
 
 ON_EC2="0"