HPCC-10537 Remove warnings from some of the compiler only tests

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #6673 from ghalliday/issue10537b

HPCC-10537 Remove warnings from some of the compiler only tests

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>