org-src-font-lock-fontify-block: Do not fold links inside src blocks

* lisp/org-src.el (org-src-font-lock-fontify-block): Overwrite link
fontification after regexp-based `org-activate-links' fontifies links
disregarding Org parser.  Hidden parts of link-looking text are
explicitly unfolded now.  This commit relies on specific fontification
order in `org-font-lock-keywords'.
(org-fold-region): Declare function.

Reported-by: Tim Loderhose <tim@loderhose.com>
Link: https://orgmode.org/list/XdWFnN3XCJ67x3SvoiVo_itGGYfboKmuWp7OxQxRZ_SGA5vgb72oWBoqTmOUUtiqUR890-kIXjI7uhlse-HFYqNVJTyVlc15zAzbP8qHVdo=@loderhose.com

lisp/org-src.el

@@ -43,6 +43,7 @@
 (declare-function org--get-expected-indentation "org" (element contentsp))
 (declare-function org-mode "org" ())
 (declare-function org--get-expected-indentation "org" (element contentsp))
+(declare-function org-fold-region "org-fold" (from to flag &optional spec-or-alias))
 (declare-function org-element-at-point "org-element" (&optional pom cached-only))
 (declare-function org-element-class "org-element" (datum &optional parent))
 (declare-function org-element-context "org-element" (&optional element))
@@ -698,6 +699,8 @@ as `org-src-fontify-natively' is non-nil."
           (when (or (facep src-face) (listp src-face))
             (font-lock-append-text-property start end 'face src-face))
 	  (font-lock-append-text-property start end 'face 'org-block))
+        ;; Clear abbreviated link folding.
+        (org-fold-region start end nil 'org-link)
 	(add-text-properties
 	 start end
 	 '(font-lock-fontified t fontified t font-lock-multiline t))