Remove compat code from some mml files

* lisp/gnus/mml-sec.el (mml-secure-passphrase-cache-expiry):
Remove compat code.

* lisp/gnus/mml-smime.el (mml-smime-openssl-sign-query):
Always use `mail-extract-address-components', since this isn't
time critical.
(mml-smime-get-dns-cert): Ditto.

* lisp/gnus/mml.el (mml-preview): Remove compat code.

lisp/gnus/mm-uu.el

@@ -290,8 +290,7 @@ If PROPERTIES is non-nil, PROPERTIES are applied to the buffer,
 see `set-text-properties'.  If PROPERTIES equals t, this means to
 apply the face `mm-uu-extract'."
   (let ((obuf (current-buffer))
-        (multi (and (boundp 'enable-multibyte-characters)
-                    enable-multibyte-characters))
+        (multi enable-multibyte-characters)
 	(coding-system buffer-file-coding-system))
     (with-current-buffer (generate-new-buffer " *mm-uu*")
       (if multi (mm-enable-multibyte) (mm-disable-multibyte))

lisp/gnus/mml-sec.el

@@ -122,10 +122,7 @@ See Info node `(message) Security'."
   :group 'message
   :type 'boolean)
 
-(defcustom mml-secure-passphrase-cache-expiry
-  (if (boundp 'password-cache-expiry)
-      password-cache-expiry
-    16)
+(defcustom mml-secure-passphrase-cache-expiry password-cache-expiry
   "How many seconds the passphrase is cached.
 Whether the passphrase is cached at all is controlled by
 `mml-secure-cache-passphrase'."

lisp/gnus/mml-smime.el

@@ -175,15 +175,12 @@ Whether the passphrase is cached at all is controlled by
   (list 'keyfile
 	(if (= (length smime-keys) 1)
 	    (cadar smime-keys)
-	  (or (let ((from (cadr (funcall (if (boundp
-					      'gnus-extract-address-components)
-					     gnus-extract-address-components
-					   'mail-extract-address-components)
-					 (or (save-excursion
-					       (save-restriction
-						 (message-narrow-to-headers)
-						 (message-fetch-field "from")))
-					     "")))))
+	  (or (let ((from (cadr (mail-extract-address-components
+				 (or (save-excursion
+				       (save-restriction
+					 (message-narrow-to-headers)
+					 (message-fetch-field "from")))
+				     "")))))
 		(and from (smime-get-key-by-email from)))
 	      (smime-get-key-by-email
 	       (gnus-completing-read "Sign this part with what signature"
@@ -204,15 +201,12 @@ Whether the passphrase is cached at all is controlled by
 	(while (not result)
 	  (setq who (read-from-minibuffer
 		     (format "%sLookup certificate for: " (or bad ""))
-		     (cadr (funcall (if (boundp
-					 'gnus-extract-address-components)
-					gnus-extract-address-components
-				      'mail-extract-address-components)
-				    (or (save-excursion
-					  (save-restriction
-					    (message-narrow-to-headers)
-					    (message-fetch-field "to")))
-					"")))))
+		     (cadr (mail-extract-address-components
+			    (or (save-excursion
+				  (save-restriction
+				    (message-narrow-to-headers)
+				    (message-fetch-field "to")))
+				"")))))
 	  (if (setq cert (smime-cert-by-dns who))
 	      (setq result (list 'certfile (buffer-name cert)))
 	    (setq bad (format-message "`%s' not found. " who))))

lisp/gnus/mml.el

@@ -1544,12 +1544,11 @@ or the `pop-to-buffer' function."
 	(message-sort-headers)
 	(mml-to-mime))
       (if raw
-	  (when (fboundp 'set-buffer-multibyte)
-	    (let ((s (buffer-string)))
-	      ;; Insert the content into unibyte buffer.
-	      (erase-buffer)
-	      (mm-disable-multibyte)
-	      (insert s)))
+	  (let ((s (buffer-string)))
+	    ;; Insert the content into unibyte buffer.
+	    (erase-buffer)
+	    (mm-disable-multibyte)
+	    (insert s))
 	(let ((gnus-newsgroup-charset (car message-posting-charset))
 	      gnus-article-prepare-hook gnus-original-article-buffer
 	      gnus-displaying-mime)