[tex4ht] java modules

[Karl Berry]

    Here is a fix for the problem that you observed.

I installed it. Thanks. That fixed the first problem, but not the second
("pushd: no other directory"). tex4ht-javahelp-xtpipes.tex did not have
the necessary \input{tex4ht-dir} (maybe you had that as a local
change). I committed that too.

By the way, when the same change is being done in several files, there's
no need to repeat the description in the ChangeLog. Just
* file1,
* file2: change.
suffices.

    I am a bit puzzled why I did not observed the same error.

I've observed that often errors happen on run N that do not happen on
run N+1. I don't usually try to clean everything before any given run.

    appropriate to disable it in the .tex by default unless do_java is
    ...
    That would be easy to do through the texh4t-dir.tex that could contain
    a switch passed from the makefile.

If you want to make a patch for that, it's fine with me. I was just
making the minimum change in the shortest possible time :).

A bigger problem is that even after running make do_java=1
and everything succeeding, running make do_java=1 again
still causes everything to be remade. That should not happen.
I did not try to trace the dependencies with make -d or whatever, though ...

Best,
Karl