Use ZLIB's crc32() function.
We need this change before D21375.
% sysctl kern.compress_user_cores=1
% kill -6 <top's pid>
% gzip -d top.core.gz
Why did you change the level?
Include zutil.h instead of zlib.h in order to pick up OS_CODE and DEF_MEM_LEVEL.
This changeset was brought from my initial changeset.
Back in that time, due to some API name conflict and few others, I couldn't include zutil.h.
Our zlib migration committed in CURRENT doesn't have this restriction and I was able to revert back.