zlib: apply upstream fix for CVE-2018-25032

Fix memory corruption when deflating (i.e., when compressing)
if the input has many distant matches.

This is direct commit to stable/11 using unmodified upstream fix
https://github.com/madler/zlib/commit/5c44459c3b28a9bd3283aaceab7c615f8020c531

Security: CVE-2018-25032