Simplify message-unique-id etc.

* lisp/gnus/message.el (message-unique-id):
* lisp/net/sasl.el (sasl-unique-id-function):
Avoid unnecessary consing and reliance on internal timestamp
format by using (time-convert nil 'integer) which typically does
no consing, instead of using (current-time) and then ignoring
the subsecond parts of the generated list.

lisp/gnus/message.el

@@ -5828,15 +5828,15 @@ In posting styles use `(\"Expires\" (make-expires-date 30))'."
 ;; You might for example insert a "." somewhere (not next to another dot
 ;; or string boundary), or modify the "fsf" string.
 (defun message-unique-id ()
-  ;; Don't use microseconds from (current-time), they may be unsupported.
+  ;; Don't use fractional seconds from timestamp; they may be unsupported.
   ;; Instead we use this randomly inited counter.
   (setq message-unique-id-char
-	(% (1+ (or message-unique-id-char
+	;; 2^16 * 25 just fits into 4 digits i base 36.
-		   (random (ash 1 20))))
+	(let ((base (* 25 25)))
-	   ;; (current-time) returns 16-bit ints,
+	  (if message-unique-id-char
-	   ;; and 2^16*25 just fits into 4 digits i base 36.
+	      (% (1+ message-unique-id-char) base)
-	   (* 25 25)))
+	    (random base))))
-  (let ((tm (current-time)))
+  (let ((tm (time-convert nil 'integer)))
     (concat
      (if (or (eq system-type 'ms-dos)
 	     ;; message-number-base36 doesn't handle bigints.
@@ -5846,10 +5846,12 @@ In posting styles use `(\"Expires\" (make-expires-date 30))'."
 	     (aset user (match-beginning 0) ?_))
 	   user)
        (message-number-base36 (user-uid) -1))
-     (message-number-base36 (+ (car tm)
+     (message-number-base36 (+ (ash tm -16)
-			       (ash (% message-unique-id-char 25) 16)) 4)
+			       (ash (% message-unique-id-char 25) 16))
-     (message-number-base36 (+ (nth 1 tm)
+			    4)
-			       (ash (/ message-unique-id-char 25) 16)) 4)
+     (message-number-base36 (+ (logand tm #xffff)
+			       (ash (/ message-unique-id-char 25) 16))
+			    4)
      ;; Append a given name, because while the generated ID is unique
      ;; to this newsreader, other newsreaders might otherwise generate
      ;; the same ID via another algorithm.

lisp/net/sasl.el

@@ -174,21 +174,24 @@ It contain at least 64 bits of entropy."
 
 ;; stolen (and renamed) from message.el
 (defun sasl-unique-id-function ()
-  ;; Don't use microseconds from (current-time), they may be unsupported.
+  ;; Don't use fractional seconds from timestamp; they may be unsupported.
   ;; Instead we use this randomly inited counter.
   (setq sasl-unique-id-char
-	(% (1+ (or sasl-unique-id-char (logand (random) (1- (ash 1 20)))))
+	;; 2^16 * 25 just fits into 4 digits i base 36.
-	   ;; (current-time) returns 16-bit ints,
+	(let ((base (* 25 25)))
-	   ;; and 2^16*25 just fits into 4 digits i base 36.
+	  (if sasl-unique-id-char
-	   (* 25 25)))
+	      (% (1+ sasl-unique-id-char) base)
-  (let ((tm (current-time)))
+	    (random base))))
+  (let ((tm (time-convert nil 'integer)))
     (concat
      (sasl-unique-id-number-base36
-      (+ (car   tm)
+      (+ (ash tm -16)
-	 (ash (% sasl-unique-id-char 25) 16)) 4)
+	 (ash (% sasl-unique-id-char 25) 16))
+      4)
      (sasl-unique-id-number-base36
-      (+ (nth 1 tm)
+      (+ (logand tm #xffff)
-	 (ash (/ sasl-unique-id-char 25) 16)) 4))))
+	 (ash (/ sasl-unique-id-char 25) 16))
+      4))))
 
 (defun sasl-unique-id-number-base36 (num len)
   (if (if (< len 0)