Enable -mpopcnt and -mlzcnt on AVX2

[klondi]

When -mpopcnt or -mlzcnt are explicitly enable or disabled (when using -march=native for example), kvazaar builds fail on older CPUs without support for these flags (see https://github.com/ultravideo/kvazaar/issues/228 and https://bugs.gentoo.org/739776 ).

Ensuring these flags are on as done with the rest of AVX2 flags solves the compilation issues, although it may be a better approach to provide a configuration option so that only the specific version matching the build system supported flags is created in such cases.

[Arizer]

Hi,

Thanks for reporting and creating a pull request.

We are currently looking into the possibility of changing the license to a more permissive one. Do you grant us the permission to use your PR with the possible future license (3-clause BSD) as well? (License issue here: https://github.com/ultravideo/kvazaar/issues/302)

[klondi]

Sure! The change is so trivial anyways that you can consider the patch under any other license Arizer!

[Arizer]

Great. Thank you.

[klondi]

Hi!

This is still an issue with 2.1.0 I have rebased the changes so they can be applied to the current master. I'm unsure how to rerun the CI tests though.

[fador]

Thanks! I ran the commit through our Gitlab CI and it seems to work so should be fine. Sorry for the delay but it's finally merged ;)

-Marko

[klondi]

Thanks Marko! Now I'll try to get the video team on Gentoo to backport this :)