fix sc_lag and sc_lagud to use the first k- or a-rate input when no initial value is given
fix sc_lag and sc_lagud to use the first k- or a-rate input when no initial value is given

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