Make the loaddefs scraping compilation output look more regular

* lisp/Makefile.in ($(lisp)/loaddefs.el): Don't output the
directories here.

* lisp/emacs-lisp/autoload.el (batch-update-autoloads--summary):
New function.
(batch-update-autoloads): Use it to output the directories we're
scraping.

This changes the compilation output from:

Directories for loaddefs: . ./calc ./calendar ./cedet ./cedet/ede
./cedet/semantic ./cedet/semantic/analyze ./cedet/semantic/bovine
./cedet/semantic/decorate ./cedet/semantic/symref ./cedet/semantic/wisent
./cedet/srecode ./emacs-lisp ./emulation ./erc ./eshell ./gnus ./image
./international ./language ./leim ./leim/ja-dic ./leim/quail ./mail ./mh-e
./net ./nxml ./org ./play ./progmodes ./textmodes ./url ./vc

(but all on one long line)

To:

  SCRAPE   . ./calc ./calendar ./cedet ./cedet/ede ./cedet/semantic
  SCRAPE   ./cedet/semantic/analyze ./cedet/semantic/bovine
  SCRAPE   ./cedet/semantic/decorate ./cedet/semantic/symref
  SCRAPE   ./cedet/semantic/wisent ./cedet/srecode ./emacs-lisp ./emulation
  SCRAPE   ./erc ./eshell ./gnus ./image ./international ./language ./leim
  SCRAPE   ./leim/ja-dic ./leim/quail ./mail ./mh-e ./net ./nxml ./org ./play
  SCRAPE   ./progmodes ./textmodes ./url ./vc

Compilation output with very long lines can be mistaken for errors
when they scroll by fast in the compilation output.  Making it look
more like normal informational output avoids this confusion.

lisp/Makefile.in

@@ -196,7 +196,6 @@ $(lisp)/finder-inf.el:
 
 autoloads .PHONY: $(lisp)/loaddefs.el
 $(lisp)/loaddefs.el: gen-lisp $(LOADDEFS)
-	@echo Directories for loaddefs: ${SUBDIRS_ALMOST}
 	$(AM_V_GEN)$(emacs) -l autoload \
 	    --eval '(setq autoload-ensure-writable t)' \
 	    --eval '(setq autoload-builtin-package-versions t)' \

lisp/emacs-lisp/autoload.el

@@ -1124,7 +1124,7 @@ write its autoloads into the specified file instead."
       ;; Elements remaining in FILES have no existing autoload sections yet.
       (let ((no-autoloads-time (or last-time '(0 0 0 0)))
             (progress (make-progress-reporter
-                       (byte-compile-info-string
+                       (byte-compile-info
                         (concat "Scraping files for "
                                 (file-relative-name
                                  generated-autoload-file)))
@@ -1167,6 +1167,19 @@ write its autoloads into the specified file instead."
       ;; file-local autoload-generated-file settings.
       (autoload-save-buffers))))
 
+(defun batch-update-autoloads--summary (strings)
+  (let ((message ""))
+    (while strings
+      (when (> (length (concat message " " (car strings))) 68)
+        (byte-compile-info message t "SCRAPE")
+        (setq message ""))
+      (setq message (if (zerop (length message))
+                        (car strings)
+                      (concat message " " (car strings))))
+      (setq strings (cdr strings)))
+    (when (> (length message) 0)
+      (byte-compile-info message t "SCRAPE"))))
+
 ;;;###autoload
 (defun batch-update-autoloads ()
   "Update loaddefs.el autoloads in batch mode.
@@ -1190,6 +1203,7 @@ should be non-nil)."
 	    (or (string-match "\\`site-" file)
 		(push (expand-file-name file) autoload-excludes)))))))
   (let ((args command-line-args-left))
+    (batch-update-autoloads--summary args)
     (setq command-line-args-left nil)
     (apply #'update-directory-autoloads args)))