[dvipdfmx] dvipdfmx: wrong exit status

[Karl Berry]

    But dvipdfmx also continues processing when there is an
    unprocessed special command, e.g., due to  syntax error.
    In this case too the output may not be as the user expects.

    For inconsistent font metrics problems, missing glyphs, and
    in various other situations, dvipdfmx just gives a warning but
    not aborts with bad status. All these situations can result in
    an inconsistent output.

First, I think it is good to continue processing in all these cases,
including a missing image, just as is done now. (dvips does too, afaik.)
There's no need to abort and not generate output.

As for which should have bad output status, none of the above seem so
critical to me as missing images; missing glyph seems like the only
other reasonable candidate for bad exit to me, if you feel like it.

The others can happen in normal use:
- unprocessed special: a document includes package X which outputs
random special Y. This is normally harmless and a bad exit would just
cause trouble. It's desirable for most unrecognized specials to just be
ignored -- aside from the warning, which is good -- and not cause failure.

- Inconsistent font metrics "shouldn't" happen, but do. We just learned
about the cmssdc10 case, which won't be fixed soon, if ever. Who knows
what other discrepancies are lurking.

Overall, I wouldn't argue for any great overhaul or widespread
aborting. Just the missing image, and perhaps missing glyph, case
are where it seems useful.

Thanks,
Karl

P.S. On another, much more important, front, do the proposed changes to
fix the weird strncmp problem look ok?