./scripts/spdxcheck.py warns Invalid License ID: Zlib

Dear Ilya, dear Mikhail,

thank you for pointing out clear original authorship and license 
information in the files you have contributed.

Due to these pointers, ./scripts/spdxcheck.py has identified these files 
licensed under the Zlib License and reports:

  lib/zlib_dfltcc/dfltcc.c: 1:28 Invalid License ID: Zlib
  lib/zlib_dfltcc/dfltcc.h: 1:28 Invalid License ID: Zlib
  lib/zlib_dfltcc/dfltcc_deflate.c: 1:28 Invalid License ID: Zlib
  lib/zlib_dfltcc/dfltcc_inflate.c: 1:28 Invalid License ID: Zlib
  lib/zlib_dfltcc/dfltcc_util.h: 1:28 Invalid License ID: Zlib

As there is currently no Zlib license text in LICENSES, I believe you must 
simply add the Zlib license text to LICENSES/deprecated. The documentation 
states deprecated licenses should only be used for existing code or for 
importing code from a different project, which is the case here.

Just in case you are not aware, more documentation on licensing is here:

  https://www.kernel.org/doc/html/latest/process/license-rules.html


Best regards,

Lukas