Minor bug fix in computing math expression
Minor bug fix in computing math expression

It was a minor typo but change the logic.
Originally:

  if ( var>=0 && var<m_num_metrics );
    return hpcrun_fmt_metric_get_value(m_list_metric_desc[var], 
              m_metrics[var]);

Fixed version:
 if ( var>=0 && var<m_num_metrics )
    return hpcrun_fmt_metric_get_value(m_list_metric_desc[var], 
              m_metrics[var]);
HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit