[tlbuild] Test failures for dvipdmfx on OpenBSD

[Mojca Miklavec]

Dear Karl,

This may not be important for TL release, but it might be worth
checking (it might point to another latent issue that would affect
other platforms as well).

The 64-bit OpenBSD 6.7 and 6.8 builders are experiencing failures for
dvipdfmx-upjf.test, but it's not deterministic (sometimes it works and
sometimes it fails):

fontmap: upjf-r -> Ryumin-Light(UPJF-UTF16-H)[noemb]
(CMap:UPJF-UTF16-HSegmentation fault (core dumped)

See:
- https://build.contextgarden.net/#/builders/76
- https://build.contextgarden.net/#/builders/79

The first failure was seen for
    http://tug.org/svn/texlive?view=revision&revision=57148
but since it doesn't always fail (one builder saw 4 and the other
builder saw 7 failures out of roughly 20 builds), the problem was
probably introduced a few commits earlier. I see quite some changes
related to dvipdfmx, but I'm not exactly sure about the best way to
test with this non-deterministic behaviour. (I'm running the builds
inside virtual machines.)

Weird enough I don't see the problem on the 32-bit version of the same
OS. I'm not excluding the option that something is wrong with the VM
either.

Mojca