I tried adding `options ZFS` to sys/conf/NOTES as part of r293070 , and unfortunately caused build errors with `LINT` because of name collisions between zfs(4) and zlib(9). I reverted the change in r293091 .
This bug is being filed to track the issue and (eventually) fix it.
This will likely need to be fixed by consolidating the two copies of zlib into one copy, and might require upgrading zlib in the kernel to something more recent..
The current plan is to remove the gzipped a.out support which will make this go away.
A commit references this bug:
Date: Tue Jul 30 05:13:17 UTC 2019
New revision: 350436
Remove gzip'ed a.out support.
The current implementation of gzipped a.out support was based
on a very old version of InfoZIP which ships with an ancient
modified version of zlib, and was removed from the GENERIC
kernel in 1999 when we moved to an ELF world.
Reviewed by: imp, kib, emaste, Yoshihiro Ota <ota at j.email.ne.jp>
Differential Revision: https://reviews.freebsd.org/D21099