Detect FreeBSD versions with broken MSG_CMSG_CLOEXEC

If we are compiling against a version of FreeBSD where MSG_CMSG_CLOEXEC
does not work, use the fallback directly. This was only fixed recently
(in https://cgit.freebsd.org/src/commit/?id=6ceacebdf52211).

Signed-off-by: Alex Richardson <Alexander.Richardson@cl.cam.ac.uk>
4 jobs for freebsd-port-rebased-on-ci-commit in 1 minute and 25 seconds
latest
Status Job ID Name Coverage
  Review
passed #10523516
check-commit

00:00:13

 
  Prep
passed #10523517
kvm
debian:buster@container-prep

00:00:18

 
  Build
failed #10523519
kvm allowed to fail
build-freebsd

00:00:53

passed #10523518
build-native

00:00:19

 
Name Stage Failure
failed
build-freebsd Build
Full log written to /root/wayland/build/meson-logs/testlog.txt
+ cleanup
+ [ -e /tmp/qemu.pid ]
+ cat /tmp/qemu.pid
+ kill 10
+ rm -f /tmp/qemu.pid
qemu-system-x86_64: terminating on signal 15 from pid 9 (sh)
Cleaning up file based variables
ERROR: Job failed: exit code 1