bug#42032: 27.0.91; Allow Lisp_User_Ptr to declare which LispObject it has reference to

[Ivan Yonchovski]

This will using Lisp_User_Ptr for lazy computation. Here it is sample
flow:

(let ((lazy (my-module-function)))
  (my-module-get lazy "foo") ;; returns "bar"
  (my-module-get lazy "foo") ;; returns "bar"
  ...
  )

ATM it is not possible to cache "bar" in lazy because it will be garbage
collected.

Thanks,
Ivan