fix segfault if non-existent csd file given to csound
fix segfault if non-existent csd file given to csound

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