refresh: Support comma-separated updater types.

* guix/scripts/refresh.scm (%options): Handle comma-separated types for
  '--type' option.
  (guix-refresh): Adjust accordingly.
  (show-help): Likewise.
* doc/guix.texi (Invoking guix refresh): Document it.

doc/guix.texi

@@ -4276,8 +4276,8 @@ inconvenient.
 
 @item --type=@var{updater}
 @itemx -t @var{updater}
-Select only packages handled by @var{updater}.  Currently, @var{updater}
-may be one of:
+Select only packages handled by @var{updater} (may be a comma-separated
+list of updaters).  Currently, @var{updater} may be one of:
 
 @table @code
 @item gnu
@@ -4292,7 +4292,7 @@ For instance, the following commands only checks for updates of Emacs
 packages hosted at @code{elpa.gnu.org} and updates of CRAN packages:
 
 @example
-$ guix refresh -t elpa -t cran
+$ guix refresh --type=elpa,cran
 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
 @end example

guix/scripts/refresh.scm

@@ -69,10 +69,13 @@ (define %options
                             arg)))))
         (option '(#\t "type") #t #f
                 (lambda (opt name arg result)
-                  (alist-cons 'updater (string->symbol arg) result)))
+                  (let* ((not-comma (char-set-complement (char-set #\,)))
+                         (names (map string->symbol
+                                     (string-tokenize arg not-comma))))
+                    (alist-cons 'updaters names result))))
         (option '(#\L "list-updaters") #f #f
                 (lambda args
-                   (list-updaters-and-exit)))
+                  (list-updaters-and-exit)))
         (option '(#\l "list-dependent") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'list-dependent? #t result)))
@@ -114,7 +117,8 @@ (define (show-help)
   -s, --select=SUBSET    select all the packages in SUBSET, one of
                          `core' or `non-core'"))
   (display (_ "
-  -t, --type=UPDATER     restrict to updates from UPDATER--e.g., 'gnu'"))
+  -t, --type=UPDATER,... restrict to updates from the specified updaters
+                         (e.g., 'gnu')"))
   (display (_ "
   -L, --list-updaters    list available updaters and exit"))
   (display (_ "
@@ -209,15 +213,15 @@ (define (parse-options)
   (define (options->updaters opts)
     ;; Return the list of updaters to use.
     (match (filter-map (match-lambda
-                         (('updater . name)
-                          (lookup-updater name))
+                         (('updaters . names)
+                          (map lookup-updater names))
                          (_ #f))
                        opts)
       (()
        ;; Use the default updaters.
        %updaters)
-      (lst
-       lst)))
+      (lists
+       (concatenate lists))))
 
   (define (keep-newest package lst)
     ;; If a newer version of PACKAGE is already in LST, return LST; otherwise