[tex-live] laulatex quiting: fix your writable cache path

[Karl Berry]

    >> +#include "ptexlib.h"
    >> #include <assert.h>
    >> -#include "ptexlib.h"

I'm testing this change now, thanks much for the quick investigation.

    would be possible to add a warning to the top of ptexlib.h just in
    case it is not? 

Yes please!  Otherwise problems will inevitably recur.  Akira?

Somehow this is the first I've ever heard of this requirement.  It is
nontrivial and painful to comply with such things.  It would be even
better to not require any particular loading order, but I suppose that
is impossible.

    Is there a #define that can be tested against portably? (EOF maybe?)

EOF sounds good to me.  Presumably also assert, which is the case at
hand.  Maybe also _POSIX_VERSION, and/or STDIN_FILENO (from unistd.h,
which could be included without stdio).  I don't think there's any way
to guarantee the warning, but if we can catch the most likely cases,
that'd be a whole lot better than nothing.

Thanks,
k