Added csoundvst_api.c.
Added csoundvst_api.c.

csound/csound,csound/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,csound/csound