HPCC-11333 Add platform support for BUILD(MAXLENGTH)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-11333 Update error message following review

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5987 from ghalliday/issue11333

HPCC-11333 Add platform support for BUILD(MAXLENGTH)

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>