Please apply the patch from PR 196226 (also available from https://reviews.freebsd.org/D12977) and build a new world (new kernel is not required) and run an exp-run.
Exp-run looks fine.
A commit references this bug: Author: jhb Date: Tue Nov 14 23:50:31 UTC 2017 New revision: 325835 URL: https://svnweb.freebsd.org/changeset/base/325835 Log: Use #if instead of #ifdef for __BSD_VISIBLE tests. __BSD_VISIBLE is always defined and it's value instead needs to be tested via #if to determine if FreeBSD-specific APIs should be exposed. PR: 196226, 223481 (exp-run) Submitted by: pluknet MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D12977 Changes: head/sys/sys/aio.h head/sys/sys/shm.h