[PD-dev] audio support changes

[Mathieu Bouchard]

I made two changes in devel_0_39's audio/midi support:

  * APIs not compiled in show up in "pd -help", with a special mention
    "(support not compiled in)". This allows the user to distinguish
    between a feature that's missing in a build, vs a syntax error.

  * those options don't give you a "unknown option" when trying them,
    it says "option -foo not compiled in this pd".

  _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada