guix build: Re-purpose '--verbosity' and add '--debug'.

The previous '--verbosity' option was misleading and rarely what users
were looking for.  The new option provides a consistent way to choose
whether or not to display the build log.

* guix/scripts/build.scm (show-build-options-help): Remove "--verbosity"
and add "--debug".
(set-build-options-from-command-line): Use the 'debug key of OPTS for
 #:verbosity.
(%standard-build-options): Change "verbosity" to "debug".  Use
'string->number*' instead of 'string->number'.
(%default-options): Change 'verbosity to 'debug and add a 'verbosity
key.
(show-help): Add '--verbosity'.
(%options): Likewise, and change '--quiet' to set the 'verbosity key of
RESULT.
(guix-build): Use 'with-status-verbosity' instead of parameterizing
CURRENT-BUILD-OUTPUT-PORT, honor the 'verbosity key of OPTS, and remove
'quiet?'.
* guix/scripts/environment.scm (show-help, %options): Add '--verbosity'.
(%default-options): Add 'debug'.
(guix-environment): Honor the 'verbosity key of OPTS.
* guix/scripts/pack.scm (%default-options): Add 'debug.
(%options, show-help): Add '--verbosity'.
(guix-pack): Honor the 'verbosity key of OPTS.
* guix/scripts/package.scm (%default-options): Add 'debug.
(show-help, %options): Add '--verbosity'.  Mark '--verbose' as
deprecated and change it to set 'verbosity.
(guix-package): Honor the 'verbosity key of OPTS and remove 'verbose?'.
* guix/scripts/pull.scm (%default-options): Add 'debug.
(show-help, %options): Add '--verbosity'.
(guix-pull): Honor the 'verbosity key of OPTS.
* guix/scripts/system.scm (show-help, %options): Add '--verbosity'.
(%default-options): Add 'debug.
(guix-system): Honor the 'verbosity key of OPTS.
* guix/scripts/archive.scm (%default-options): Add 'debug,
'print-build-trace?, 'print-extended-build-trace?, and
'multiplexed-build-output?.
(show-help, %options): Add '--verbosity'.
(export-from-store): Remove call to 'set-build-options-from-command-line'.
(guix-archive): Wrap body in 'with-status-verbosity'. Add call to
'set-build-options-from-command-line.
* doc/guix.texi (Common Build Options): Document '--verbosity' and
'--debug'.
(Additional Build Options): Adjust description of '--quiet'.

guix/scripts/system.scm

@@ -1015,6 +1015,8 @@ Some ACTIONS support additional ARGS.\n"))
       --full-boot        for 'vm', make a full boot sequence"))
   (display (G_ "
       --skip-checks      skip file system and initrd module safety checks"))
+  (display (G_ "
+  -v, --verbosity=LEVEL  use the given verbosity LEVEL"))
   (newline)
   (display (G_ "
   -h, --help             display this help and exit"))
@@ -1074,6 +1076,11 @@ Some ACTIONS support additional ARGS.\n"))
          (option '(#\n "dry-run") #f #f
                  (lambda (opt name arg result)
                    (alist-cons 'dry-run? #t (alist-cons 'graft? #f result))))
+         (option '(#\v "verbosity") #t #f
+                 (lambda (opt name arg result)
+                   (let ((level (string->number* arg)))
+                     (alist-cons 'verbosity level
+                                 (alist-delete 'verbosity result)))))
          (option '(#\s "system") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'system arg
@@ -1092,7 +1099,8 @@ Some ACTIONS support additional ARGS.\n"))
     (print-extended-build-trace? . #t)
     (multiplexed-build-output? . #t)
     (graft? . #t)
-    (verbosity . 0)
+    (debug . 0)
+    (verbosity . #f)                              ;default
     (file-system-type . "ext4")
     (image-size . guess)
     (install-bootloader? . #t)))
@@ -1267,8 +1275,9 @@ argument list and OPTS is the option alist."
            (args     (option-arguments opts))
            (command  (assoc-ref opts 'action)))
       (parameterize ((%graft? (assoc-ref opts 'graft?)))
-        (with-status-verbosity (if (memq command '(init reconfigure))
-                                   1 2)
+        (with-status-verbosity (or (assoc-ref opts 'verbosity)
+                                   (if (memq command '(init reconfigure))
+                                       1 2))
           (process-command command args opts))))))
 
 ;;; Local Variables: