DERBY-6012: Print thread dump and dump javacore if NetworkServerTestSetup has to kill off the Network Server start up process due to timeout

Incremental improvement for error reporting in the case of timeouts.

Patch file: derby-6012-1a-error_reporting.diff


git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1448941 13f79535-47bb-0310-9956-ffa450edef68