Add optimized crc32 for Power 8+ processors

[mmatti-sw]

This is a pull request to include all Power8 optimisations rebased to v1.2.13. The reference PR is https://github.com/madler/zlib/pull/478

[Neustradamus]

@madler: Can you look?

[ljavorsk]

I've tried to apply your patch on top of the patch from https://github.com/madler/zlib/pull/410 and it has some rejected hunks (configure.rej Makefile.in.rej ; I can sent you the output if you want).

The previous patch (https://github.com/madler/zlib/pull/478) was rebased on top of that patch, could you please preserve this order?

[nmoinvaz]

The patches for Power are also maintained and incorporated in zlib-ng if anybody is interested.

[ljavorsk]

Okay, @iii-i has rebased his patch on top of yours and provided it to me.

I would like to agree on the order in which you'll have them applied, so I don't need to change it too often. Is that okay with you?

[mmatti-sw]

I am ok with any order you or @iii-i would like to follow.

[iii-i]

I'd prefer POWER patches to go first, since they provide a foundation for adding optimized CRC32 implementations.

[ljavorsk]

Okay, I agree with that. Thank you

[ljavorsk]

Hi, could you please rebase your patches on top of zlib-1.3 version?

[Neustradamus]

@ljavorsk: Have you seen the @mmatti-sw PR?

• https://github.com/madler/zlib/pull/857

[ljavorsk]

Hi, sorry @mmatti-sw for the inconvenience. We've transitioned to zlib-ng from Fedora 40, and thus we don't plan to rebase the zlib anymore.

This means, that you can fully focus on the zlib-ng PRs from now on.