[tz] Question about bug seen in OpenBSD and FreeBSD related to tzname

Wed Nov 20 08:17:23 UTC 2019

Hello!  Earlier this month, I noticed bugs in OpenBSD and FreeBSD
related to tzname's values.
https://marc.info/?l=openbsd-bugs&m=157379849727998&w=2
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=241978
I noticed that both those OSes share relevant code with tzcode.
How would I best test this stuff out with a recent release of tzcode?
(i.e. how to make sure I'm including headers only from the 2019c
tarball and not from my OS, when possible)