HPCC-9146 - Archiving failing to archive generated dlls

A bug introduced long ago, was causing archiveWorkUnit to fail
to archive both the Dali Generateddll entries and the associated
physical files.
As a consequence Dali has been filling up with orphaned/old
GeneratedDll entries, which overtime has degraded performance

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>