HPCC-8826 Build errors on java plugin in EE build

Was not finding generated build-config.h

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #3993 from richardkchapman/java-ee-build

HPCC-8826 Build errors on java plugin in EE build

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>