HPCC-11825 Fix issues with some versions of ICU (post 5.0?)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6169 from ghalliday/issue11825

HPCC-11825 Fix issues with some versions of ICU (post 5.0?)

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>