perl-net-ping: bump to version 2.71
The license file hash is changed due to:
- Changes in the README file unrelated to the licensing terms.
- Update of the copyright year (2017 changed to 2017-2018)
Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>