lisp/org.el: Don't fontify headlines with "::" as description items

* lisp/org.el (org-set-font-lock-defaults): Avoid fontifying headlines
with "::" as description list items.

Lists can start with "*", but "*" must not be at the beginning of
line.  Old regexp did not require whitespace before "*" in description
list items.

Reported-by: Ypo <ypuntot@gmail.com>
Link: https://orgmode.org/list/5adcfcda-35de-8281-a1ff-18d1c95bbde6@gmail.com/

lisp/org.el

@@ -5698,7 +5698,7 @@ needs to be inserted at a specific position in the font-lock sequence.")
 	     '("\\[\\([0-9]*%\\)\\]\\|\\[\\([0-9]*\\)/\\([0-9]*\\)\\]"
 	       (0 (org-get-checkbox-statistics-face) t)))
 	   ;; Description list items
-	   '("^[ \t]*[-+*][ \t]+\\(.*?[ \t]+::\\)\\([ \t]+\\|$\\)"
+           '("\\(?:^[ \t]*[-+]\\|^[ \t]+[*]\\)[ \t]+\\(.*?[ \t]+::\\)\\([ \t]+\\|$\\)"
 	     1 'org-list-dt prepend)
 	   ;; ARCHIVEd headings
 	   (list (concat