[tlbuild] ptex ini creation seg faults on OpenBSD

[Karl Berry]

    seems to be a bug/glitch because get_jfm_pos should certainly not be called
    with f=0= null_font!

Some evidence that it's not a compiler bug would be useful, since no
other platform is not reporting this.  E.g., compile with just -g.  Try
a different compiler version.

(As for malloc issues, personally, I've had the most luck with
electricfence, if available vm is sufficient.  But I'm pretty skeptical
that this is a malloc issue.)

Anyway, we won't be fixing this or making any changes in the sources for
tl'10.

Best,
Karl