rpm: switch to version 4.13.0

rpm: switch to version 4.13.0

Switch from RPM5's implementation to rpm.org's more active stream [1].

The history of RPM and the common RPM5-fork is covered in an LWN article
"Who maintains RPM?" [2]. Since rpm.org's implementation is used/
maintained on most RPM-based distributions as well as a series of other
minor details (see [3]), the switch is being made.

[1]: http://lists.buildroot.org/pipermail/buildroot/2015-August/137580.html
[2]: https://lwn.net/Articles/196523/
[3]: https://patchwork.ozlabs.org/patch/668151/

Signed-off-by: James Knight <james.knight@rockwellcollins.com>
[Thomas: adjust licensing.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>