Honor SOURCE_DATE_EPOCH variable to avoid non-determinism in generated
"autoloads" files.

--- a/lisp/emacs-lisp/autoload.el
+++ b/lisp/emacs-lisp/autoload.el
@@ -419,8 +419,12 @@
   ;;              nil t))
   ;;        (match-end 2))))
   (insert generate-autoload-section-header)
-  (prin1 `(autoloads ,autoloads ,load-name ,file ,time)
-	 outbuf)
+  (let* ((env  (getenv "SOURCE_DATE_EPOCH"))
+         (time (if env
+                   (seconds-to-time (string-to-number env))
+                 time)))
+    (prin1 `(autoloads ,autoloads ,load-name ,file ,time)
+           outbuf))
   (terpri outbuf)
   ;; Break that line at spaces, to avoid very long lines.
   ;; Make each sub-line into a comment.
;'>
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<div class='path'>path: <a href='/guix/log/?id=d4aca38b50d75cff9bd065a855e7368a51843db4'>root</a>/<a href='/guix/log/tests?id=d4aca38b50d75cff9bd065a855e7368a51843db4'>tests</a>/<a href='/guix/log/tests/elpa.scm?id=d4aca38b50d75cff9bd065a855e7368a51843db4'>elpa.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/elpa.scm?id=d4aca38b50d75cff9bd065a855e7368a51843db4&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-02 22:09:23 +0100'>2020-12-02</span></td><td><a href='/guix/commit/tests/elpa.scm?id=bea3b17739fc591b8cf6db1f8d28a6f6c9585577'>import: utils: 'recursive-import' accepts an optional version parameter.</a><span class='msg-avail'>...</span></td><td>Martin Becze</td></tr>
<tr><td><span title='2020-01-16 23:14:05 +0100'>2020-01-16</span></td><td><a href='/guix/commit/tests/elpa.scm?id=9d6c6cb20ef240221fc9a8e155f4bfa53e71bce4'>import: elpa: Rewrite test to use an HTTP server instead of mocking.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>