[tlbuild] Broken tests for mendexk on arm

[Karl Berry]

I'm planning to release (freezing today) with the failing (on some
platforms) test. I mean, I could put exit 0 (or better, exit 77) at the
top of the test to placate CI, but that doesn't really seem better than
failing to me, since failing is the truth. Maybe I'll put in the exit
after the release.

As for debugging, given access to a machine where it fails, seems to me
it is no different than any other bug: have to collect the input, run
the program under the debugger, understand what is happening. I have no
such machine.

I have had no chance myself to even look at the failing test, nor will I
be able to do so for quite a while to come. --best, karl.