Remove time-date debugging scaffolding

Problem reported by Lars Ingebrigtsen in:
https://lists.gnu.org/r/emacs-devel/2019-05/msg00721.html
* lisp/calendar/time-date.el (date-to-time):
Use plain condition-case, not condition-case-unless-debug.

lisp/calendar/time-date.el

@@ -156,7 +156,7 @@ If DATE lacks timezone information, GMT is assumed."
      (let ((overflow-error '(error "Specified time is not representable")))
        (if (equal err overflow-error)
 	   (signal (car err) (cdr err))
-	 (condition-case-unless-debug err
+	 (condition-case err
 	     (encode-time (parse-time-string
 			   (timezone-make-date-arpa-standard date)))
 	   (error