installer: Display language and territory names natively.

* gnu/installer.scm (installer-program): Add calls to 'bindtextdomain'.
* gnu/installer/newt/locale.scm (run-locale-page) <language, territory>:
Add calls to 'gettext'.

gnu/installer.scm

@@ -343,6 +343,16 @@ (define installer-builder
             ;; Add some binaries used by the installers to PATH.
             #$set-installer-path
 
+            ;; Arrange for language and territory name translations to be
+            ;; available.  We need them at run time, not just compile time,
+            ;; because some territories have several corresponding languages
+            ;; (e.g., "French" is always displayed as "français", but
+            ;; "Belgium" could be translated to Dutch, French, or German.)
+            (bindtextdomain "iso_639-3"           ;languages
+                            #+(file-append iso-codes "/share/locale"))
+            (bindtextdomain "iso_3166-1"          ;territories
+                            #+(file-append iso-codes "/share/locale"))
+
             (let* ((current-installer newt-installer)
                    (steps (#$steps current-installer)))
               ((installer-init current-installer))

gnu/installer/newt/locale.scm

 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -161,7 +162,13 @@ (define locale-steps
          (run-language-page
           (sort-languages
            (delete-duplicates (map locale-language supported-locales)))
-          (cut language-code->language-name iso639-languages <>)))))
+          (lambda (language)
+            (let ((english (language-code->language-name iso639-languages
+                                                         language)))
+              (setenv "LANGUAGE" language)
+              (let ((native (gettext english "iso_639-3")))
+                (unsetenv "LANGUAGE")
+                native)))))))
      (installer-step
       (id 'territory)
       (compute
@@ -175,10 +182,11 @@ (define locale-steps
            ;; supported by the previously selected language.
            (run-territory-page
             (delete-duplicates (map locale-territory locales))
-            (lambda (territory-code)
-              (if territory-code
-                  (territory-code->territory-name iso3166-territories
-                                                  territory-code)
+            (lambda (territory)
+              (if territory
+                  (let ((english (territory-code->territory-name
+                                  iso3166-territories territory)))
+                    (gettext english "iso_3166-1"))
                   (G_ "No location"))))))))
      (installer-step
       (id 'codeset)