Remove repeated unary function calls in an FGL object to create an object that might be smaller to print.
This preserves the structure of the input object except that nested calls of the same unary function are replaced by a bogus call of the function on two arguments: the number of nestings and the argument to the innermost call. For example:
(:g-apply intcdr (:g-apply intcdr (:g-apply intcdr (:g-var . x))))
is replaced with
(:g-apply intcdr 3 (:g-var x))