Clarify lexvar restrictions for add-to-ordered-list, add-to-history

* lisp/subr.el (add-to-ordered-list, add-to-history):
* doc/lispref/lists.texi (List Variables):
* doc/lispref/minibuf.texi (Minibuffer History):
Note in the doc string and manual that the variable arguments to
add-to-ordered-list and add-to-history cannot refer to a lexical
variable (bug#39373).

Author: mattiase

doc/lispref/lists.texi

@@ -832,6 +832,7 @@ and unlike @code{setq}.  Quote the argument yourself if necessary.
 
 The ordering information is stored in a hash table on @var{symbol}'s
 @code{list-order} property.
+@var{symbol} cannot refer to a lexical variable.
 @end defun
 
 Here's a scenario showing how to use @code{add-to-ordered-list}:

doc/lispref/minibuf.texi

@@ -572,6 +572,7 @@ and returns the updated history list.  It limits the list length to
 the value of @var{maxelt} (if non-@code{nil}) or @code{history-length}
 (described below).  The possible values of @var{maxelt} have the same
 meaning as the values of @code{history-length}.
+@var{history-var} cannot refer to a lexical variable.
 
 Normally, @code{add-to-history} removes duplicate members from the
 history list if @code{history-delete-duplicates} is non-@code{nil}.

lisp/subr.el

@@ -1935,6 +1935,7 @@ of ELEMENT if it has one.
 
 The list order for each element is stored in LIST-VAR's
 `list-order' property.
+LIST-VAR cannot refer to a lexical variable.
 
 The return value is the new value of LIST-VAR."
   (let ((ordering (get list-var 'list-order)))
@@ -1963,7 +1964,8 @@ variable.  The possible values of maximum length have the same meaning as
 the values of `history-length'.
 Remove duplicates of NEWELT if `history-delete-duplicates' is non-nil.
 If optional fourth arg KEEP-ALL is non-nil, add NEWELT to history even
-if it is empty or duplicates the most recent entry in the history."
+if it is empty or duplicates the most recent entry in the history.
+HISTORY-VAR cannot refer to a lexical variable."
   (unless maxelt
     (setq maxelt (or (get history-var 'history-length)
 		     history-length)))