Fix issue introduced when python bindings for reporter were added
Fix issue introduced when python bindings for reporter were added

- When the rank is not the root rank, the vector is empty.
- When assigning to "back()" this results in a segmentation fault.

Signed-off-by: Brad Geltz <e42f3ad4099980ea02f08e076efbee5cf9d4a803@intel.com>

geopm/geopm,geopm/geopm,cmcantalupo/geopm,cmcantalupo/geopm,geopm/geopm,geopm/geopm,geopm/geopm,cmcantalupo/geopm,cmcantalupo/geopm,cmcantalupo/geopm