HPCC-9084 Delimit JSON across multiple Roxie ouputs

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
HPCC-9084 Add comment clarifying transfer of ownership

Signed-off-by: Anthony Fishbeck <Anthony.Fishbeck@lexisnexis.com>
Merge pull request #4210 from afishbeck/json_fixes

HPCC-9084 Delimit JSON across multiple Roxie ouputs

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>