org-element: Fix parsing path starting with ~

* lisp/org-element.el (org-element-link-parser): Do not prepend "//"
  to paths starting with "~".

Since b1dcd0fb0bec6b523c900bc1304fbe834c21697d, link parser doesn't
expand file names anymore. We need to prevent it from "fixing" paths
starting with "~", as it can cause trouble to some
exporters (e.g. latex).

lisp/org-element.el

@@ -3053,8 +3053,8 @@ Assume point is at the beginning of the link."
 	    (setq search-option (match-string 1 path)
 		  path (replace-match "" nil nil path)))
 	  ;; Normalize URI.
-	  (when (and (not (org-string-match-p "\\`//" path))
-		     (file-name-absolute-p path))
+	  (when (and (file-name-absolute-p path)
+		     (not (org-string-match-p "\\`[/~]/" path)))
 	    (setq path (concat "//" path)))
 	  ;; Make sure TYPE always reports "file".
 	  (setq type "file"))