lib/zlib: Fix a bug when getting a gzip header extra field

lib/zlib: Fix a bug when getting a gzip header extra field

This fixes CVE-2022-37434 [1] and bases on 2 commits from Mark
Adler's zlib master repo - the original fix of CVE bug [2] and
the fix for the fix [3].

[1]
https://github.com/advisories/GHSA-cfmr-vrgj-vqwv
[2]
https://github.com/madler/zlib/commit/eff308af425b67093bab25f80f1ae950166bece1
[3]
https://github.com/madler/zlib/commit/1eb7682f845ac9e9bf9ae35bbfb3bad5dacbd91d

Fixes: e89516f031d ("zlib: split up to match original source tree")
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>