Java 9: Add jaxb-api dependency
Java 9: Add jaxb-api dependency

.. to verify that module-info.class can be handled without
   throwing an exception.

vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa,vespa-engine/vespa