HPCC-10459 Streamed dataset support for R

Fix build break after Java streaming support merge.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5545 from richardkchapman/r-stream-buildbreak

HPCC-10459 Streamed dataset support for R

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>