[grog] Certain preprocessors not recognized

[Morten Bo Johansen]

Hi

Unless I misunderstand something, shouldn't grog detect e.g. a
.cstart macro in a document and then come up with a suggestion
that includes the "-j" argument for the chem(1) preprocessor?

  ~/ % echo .cstart | ./grog.pl
  groff -

These do not work either:

  'lilypond', 'glilypond',
  'Perl',     'gperl',
  'pinyin',   'gpinyin',
  
This is both with the git version of groff and with 1.23.0

Thanks,
Morten