POSIX explicitly states that the application must declare union semun.
This makes no sense, but it is what it is. This brings us into line
with Linux, MacOS/Darwin, and NetBSD.
In a ports exp-run a moderate number of ports fail due to a lack of
approprate autotools-like discovery mechanisms or local patches. A
commit to address them will follow shortly.
PR: 224300, 224443 (exp-run)
Reviewed by: emaste, jhb, kib
Exp-run by: antoine
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14492
da9d8a0895