elfutils: bump to version 0.171

elfutils: bump to version 0.171

Drop the po/ disable patch; not needed anymore.

Drop the __mempcpy compatibility patch; __mempcpy is not used anymore.

Refresh the -Werror removal patch; still needed, unfortunately.

Renumber the remaining patches.

Add GPLv3 license file.

Add license files hash.

[Peter: drop security reference, was added post-release]
Cc: Stefan Fröberg <stefan.froberg@petroprogram.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>