[committed] fix new warning in symbols.c

[Eric Christopher]

> >  
> > -  return &s->sy_value.X_add_number;
> > +  return (valueT *)&s->sy_value.X_add_number;
> 
> Slightly better is to return the same type as sy_value.X_add_number, and
> cast lsy_value.  I've made that change, and would have beaten you to the
> commit if I hadn't been properly testing it.  :)
> 

Quite. I didn't actually look closely at the code beyond the return type
of the function.

thanks.

-eric