mm-uu.el: Don't dissect patch part

This fixes a bug that the patch part is broken in the article
<87inpjzhpb.fsf@users.sourceforge.net> in the bug-gnu-emacs list.

* lisp/gnus/mm-uu.el (mm-uu-dissect-text-parts):
Don't dissect patch part.

lisp/gnus/mm-uu.el

@@ -711,6 +711,8 @@ Assume text has been decoded if DECODED is non-nil."
 		    ;; Mutt still uses application/pgp even though
 		    ;; it has already been withdrawn.
 		    (string-match "\\`text/\\|\\`application/pgp\\'" type)
+		    (not
+		     (string-match "\\`text/x-\\(?:diff\\|patch\\)\\'" type))
                     (equal (car (mm-handle-disposition handle))
                            "inline")
 		    (setq