DERBY-6181; fix AutoloadTest to support running concurrently when different base ports are specified.
  Re-enable the test, passing the baseport on to when set, including on to spawned processes.


git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1480462 13f79535-47bb-0310-9956-ffa450edef68