gnu: Add ‘libc-locales-for-target’ and related.

Partly fixes <https://issues.guix.gnu.org/66472>.

This is a followup to 95ea1277ae.

* gnu/packages/base.scm (glibc-locales/hurd): New variable
(libc-locales-for-target): Use it in new procedure.
(libc-utf8-locales-for-target): New procedure.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>
Change-Id: I16e187fcc65a5d4a3b065066b45ef9e45d1875f6

gnu/packages/base.scm

@@ -76,6 +76,8 @@
   #:use-module (srfi srfi-26)
   #:export (glibc
             libc-for-target
+            libc-locales-for-target
+            libc-utf8-locales-for-target
             make-ld-wrapper
             libiconv-if-needed
             %final-inputs))
@@ -1526,6 +1528,23 @@ command.")
     (_
      glibc)))
 
+(define-public glibc-locales/hurd
+  (make-glibc-locales glibc/hurd))
+
+(define* (libc-locales-for-target #:optional
+                                  (target (or (%current-target-system)
+                                              (%current-system))))
+  (if (target-hurd? target)
+      glibc-locales/hurd
+      glibc-locales))
+
+(define* (libc-utf8-locales-for-target #:optional
+                                       (target (or (%current-target-system)
+                                                   (%current-system))))
+  (if (target-hurd? target)
+      glibc-utf8-locales/hurd
+      glibc-utf8-locales))
+
 (define-public tzdata
   (package
     (name "tzdata")