made cmake build faust opcodes only if llvm and faust were both found
made cmake build faust opcodes only if llvm and faust were both found

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