HPCC-11050 Download c++ file option doesn't work in new eclwatch

Fixes HPCC-11050

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #5619 from GordonSmith/HPCC-11050

HPCC-11050 Download c++ file option doesn't work in new eclwatch

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>