Simplify a few timestamps

* lisp/calendar/time-date.el (safe-date-to-time):
* lisp/calendar/timeclock.el (timeclock-generate-report):
* lisp/epg.el (epg--start):
* lisp/gnus/gnus-demon.el (gnus-demon-nntp-close-connection):
* lisp/gnus/gnus-util.el (gnus-date-get-time):
* lisp/gnus/nnheader.el (nnheader-last-message-time):
* lisp/gnus/nnrss.el (nnrss-request-expire-articles):
* lisp/vc/ediff-util.el (ediff-command-begin-time)
(ediff-calc-command-time, ediff-profile):
Prefer an integer like 0 to a timestamp list like (0 0)
where either will do.

lisp/calendar/time-date.el

@@ -256,10 +256,10 @@ Returns a floating point number."
 ;;;###autoload
 (defun safe-date-to-time (date)
   "Parse a string DATE that represents a date-time and return a time value.
-If DATE is malformed, return a time value of zeros."
+If DATE is malformed, return a time value of zero."
   (condition-case ()
       (date-to-time date)
-    (error '(0 0))))
+    (error 0)))
 
 
 ;;;###autoload

lisp/calendar/timeclock.el

@@ -1247,7 +1247,7 @@ HTML-P is non-nil, HTML markup is added."
 	       (time-out (vector (list t) (list t) (list t) (list t) (list t)))
 	       (breaks   (vector (list t) (list t) (list t) (list t) (list t)))
 	       (workday  (vector (list t) (list t) (list t) (list t) (list t)))
-	       (lengths  (vector '(0 0) thirty-days-ago three-months-ago
+	       (lengths  (vector 0 thirty-days-ago three-months-ago
 				 six-months-ago one-year-ago)))
 	  ;; collect statistics from complete timelog
 	  (dolist (day day-list)

lisp/epg.el

@@ -606,7 +606,7 @@ callback data (if any)."
 	 process
 	 terminal-name
 	 agent-file
-	 (agent-mtime '(0 0 0 0)))
+	 (agent-mtime 0))
     ;; Set GPG_TTY and TERM for pinentry-curses.  Note that we can't
     ;; use `terminal-name' here to get the real pty name for the child
     ;; process, though /dev/fd/0" is not portable.
@@ -633,7 +633,7 @@ callback data (if any)."
       (setq agent-file (match-string 1 agent-info)
 	    agent-mtime (or (file-attribute-modification-time
 			     (file-attributes agent-file))
-			    '(0 0 0 0))))
+			    0)))
     (if epg-debug
 	(save-excursion
 	  (unless epg-debug-buffer

lisp/gnus/gnus-demon.el

@@ -222,7 +222,7 @@ minutes, the connection is closed."
 
 (defun gnus-demon-nntp-close-connection ()
   (save-window-excursion
-    (when (time-less-p '(0 300) (time-since nntp-last-command-time))
+    (when (time-less-p 300 (time-since nntp-last-command-time))
       (nntp-close-server))))
 
 (defun gnus-demon-add-scanmail ()

lisp/gnus/gnus-util.el

@@ -383,7 +383,7 @@ Cache the result as a text property stored in DATE."
   ;; Either return the cached value...
   `(let ((d ,date))
      (if (equal "" d)
-	 '(0 0)
+	 0
        (or (get-text-property 0 'gnus-time d)
 	   ;; or compute the value...
 	   (let ((time (safe-date-to-time d)))

lisp/gnus/nnheader.el

@@ -1055,7 +1055,7 @@ See `find-file-noselect' for the arguments."
 				     (or ,end (point-max)))
 		'(buffer-string)))))
 
-(defvar nnheader-last-message-time '(0 0))
+(defvar nnheader-last-message-time 0)
 (defun nnheader-message-maybe (&rest args)
   (let ((now (current-time)))
     (when (time-less-p 1 (time-subtract now nnheader-last-message-time))

lisp/gnus/nnrss.el

@@ -325,7 +325,7 @@ for decoding when the cdr that the data specify is not available.")
 	       (nnmail-expired-article-p
 		group
 		(if (listp (setq days (nth 1 e))) days
-		  (days-to-time (- days (time-to-days '(0 0)))))
+		  (days-to-time (- days (time-to-days 0))))
 		force))
 	  (setq nnrss-group-data (delq e nnrss-group-data)
 		changed t)

lisp/vc/ediff-util.el

@@ -4094,11 +4094,11 @@ Mail anyway? (y or n) ")
 
 ;;; Debug
 
-(ediff-defvar-local ediff-command-begin-time '(0 0 0))
+(ediff-defvar-local ediff-command-begin-time 0)
 
 ;; calculate time used by command
 (defun ediff-calc-command-time ()
-  (or (equal ediff-command-begin-time '(0 0 0))
+  (or (equal ediff-command-begin-time 0)
       (message "Elapsed time: %g second(s)"
 	       (float-time (time-since ediff-command-begin-time)))))
 
@@ -4112,10 +4112,10 @@ Mail anyway? (y or n) ")
 
   (let ((pre-hook 'pre-command-hook)
 	(post-hook 'post-command-hook))
-    (if (not (equal ediff-command-begin-time '(0 0 0)))
+    (if (not (equal ediff-command-begin-time 0))
 	(progn (remove-hook pre-hook 'ediff-save-time)
 	       (remove-hook post-hook 'ediff-calc-command-time)
-	       (setq ediff-command-begin-time '(0 0 0))
+	       (setq ediff-command-begin-time 0)
 	       (message "Ediff profiling disabled"))
       (add-hook pre-hook 'ediff-save-time t 'local)
       (add-hook post-hook 'ediff-calc-command-time nil 'local)