add libmysqlclient-dev so that XOS API docs can be built

Fail job when errors occur in documentation build

Change-Id: If28222f9c3b38d62256d8242a95ad6923eb2817e
diff --git a/jjb/docs.yaml b/jjb/docs.yaml
index c7fa344..f9be3f8 100644
--- a/jjb/docs.yaml
+++ b/jjb/docs.yaml
@@ -152,6 +152,7 @@
     builders:
       - shell: |
           #!/usr/bin/env bash
+          set -e -o pipefail
 
           # Set up the ssh host keys for the docs host
           mkdir -p ~/.ssh