HPCC-8902 #workunit ('cluster', 'xxx') not supported by eclccserver

Make sure that the cluster info is cloned from the generated workunit.

Add code to eclccserver to reload the cluster after compilation, and
check it is valid.

Add code to ecl run to reload the cluster after compilation.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4930 from richardkchapman/hash-workunit

HPCC-8902 #workunit ('cluster', 'xxx') not supported by eclccserver

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>