Increase build timeout

Change-Id: I8d7e7e2593d3aef3ad40f344cf7b76f74583e640
diff --git a/jjb/siab-e2e.yaml b/jjb/siab-e2e.yaml
index 589773f..ee8e720 100644
--- a/jjb/siab-e2e.yaml
+++ b/jjb/siab-e2e.yaml
@@ -7,6 +7,7 @@
     refspec: 'refs/heads/master'
     failure-email-address: 'andy@opennetworking.org'
     timed-trigger: '{every-four-hours}'
+    build-timeout: 20
     jobs:
       - 'siab-e2e-att'