Create junit xml result output from unit tests.
Create junit xml result output from unit tests.

- Default location is the same as the gtest link directory where the log go.
- If GTEST_XML_DIR is set in the environment the output will be placed there.

Change-Id: If27e8b6ab2c96615b9ce34bef1a70f7fae365e14
Signed-off-by: Christopher M. Cantalupo <9cf3ecca60a3dd7112ab0e7250bedb8a752e3958@intel.com>

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