v2.2.1
d54e3769be0c522015b784eca2af258b1c026107

https://github.com/zlib-ng/zlib-ng/releases/tag/2.2.1

We have removed the following folders from our local copy as these files are not needed for our compilation:

- zlib-ng/doc/
- zlib-ng/test/
- zlib-ng/arch/s390/self-hosted-builder/

Also, if the next version does not yet contain the fixes included in 12bc7edc73308f017ec40c6b2db694a6e3490ac2, cherry-pick it as a patch.
