[tlbuild] Building on Macintosh

[Karl Berry]

    Intel and PowerPC now fail the [ttfdump] test 

I fail to see how a change in chktex (as opposed to a library) can
affect ttfdump.

   with various core dumps. 

At least core dumps are usually easier to debug than test failures.

    I have formed a suspicion that programmers are more and more working with
    64 bit machines.

Certainly true, but that doesn't mean we can stop supporting them.

Feel free to configure --disable-ttfdump to ignore the problem.

k