[dvipdfmx] silencing mktexpk

[Karl Berry]

Hi Shunsaku. Igor asked me:

    could you please say if there is a way to silence this message
    which I get on stderr from "dvipdfmx -q"? (notice the `-q' - I want it
    to be quiet!)

        kpathsea: Running mktexpk --mfmode / --bdpi 600 --mag 1+0/600
    --dpi 600 manfnt

    (2 lines in total - the first line is empty)

I don't believe there's a way to silence this msg to stderr with a
user-set envvar. But it can be made silenceable with a change in the
code. In dvipdfmx.c, after the kpse_init_prog call, insert (I think):

  kpse_make_tex_discard_errors = really_quiet;

This should translate to setting the kpse->make_tex_discard_errors
member in the kpse instance, and thus the code in tex-make.c that
outputs that progress report will be skipped:

  if (!kpse->make_tex_discard_errors) {
    fprintf (stderr, "\nkpathsea: Running");
    ...

I suggest that place in the code (or maybe it should be after the 
/* Setup Options */ comment following, after the second pass over the
args, I'm not sure), merely dvips does it then. In dvips.c:

   kpse_init_prog ("DVIPS", actualdpi, mfmode, "cmr10");
   kpse_make_tex_discard_errors = quiet;

I admit I have not tested any of the above. I hope you can take a look.

Thanks,
Karl

P.S. I noticed the PRODUCER string in dvipdfmx.c has Copyright...2020.
Should be updated. Also in xbb.c, any source files that have been
updated this year, and wherever else ...