HPCC-10525 Fix regression in windows constant folding (wrong flag tested)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6412 from ghalliday/issue10525fix

HPCC-10525 Fix regression in windows constant folding (wrong flag tested)

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>