Fix compilation error by providing empty array and #events of zero for power6.
Fix compilation error by providing empty array and #events of zero for
power6.

pyrovski/papi,pyrovski/papi,arm-hpc/papi,arm-hpc/papi,pyrovski/papi,pyrovski/papi,arm-hpc/papi,pyrovski/papi,pyrovski/papi,pyrovski/papi,arm-hpc/papi,arm-hpc/papi,pyrovski/papi,arm-hpc/papi,arm-hpc/papi