INTERNAL - OSX/Clang build break

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4756 from richardkchapman/mac-build-break

INTERNAL - OSX/Clang build break

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>