Signed-off-by: Arthur Gautier <baloo@gandi.net>

This adds libc-test support for Freebsd10 and a CI build job that tests
FreeBSD10 with LIBC_CI only.

Currently, libc supports and detects freebsd11 and freebsd13
Unknown versions, like freebsd13, is treated as freebsd11.
This patch solve the issues, detecting freebsd13 and treating it like
freebsd12.
Inverting the logic not(freebsd12) -> freebsd11 where possible

Currently, libc supports and detects freebsd11 and freebsd13
Unknown versions, like freebsd13, is treated as freebsd11.
This patch solve the issues, detecting freebsd13 and treating it like
freebsd12.
Inverting the logic not(freebsd12) -> freebsd11 where possible

These constants have already been deprecated for a few releases with
a deprecation notice, so they can finally be removed.

Closes rust-lang/libc#665

Per discussion in #1410, this is necessary to avoid struct size mismatches between Rust and C on
systems with glibc < 2.28.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

This was added in Linux 5.1 and will only show up in the next glibc
release, thus skip in tests.