S. Riette Sept 23: add --computeRefIfNeeded and --onlyIfNeeded switches to check_commit_mesonh

    --onlyIfNeeded allows to call check_commit_ial and compuation (pack creation,
                   compilation, execution) are performed only if needed

    --computeRefIfNeeded with this switch, if the reference simulation does not
                         exist, this reference simulation is built before
                         performing the comparison