git-download: Use C.UTF-8 and remove dependency on ‘glibc-utf8-locales’.

This is a followup to 1cebc334a77030c0c94955981652f4df7608c9e3.

* guix/git-download.scm (git-fetch/in-band*)[glibc-locales]: Remove.
[build]: Leave ‘GUIX_LOCPATH’ unset.  Use “C.UTF-8” instead of
“en_US.utf8”.

Change-Id: I268361c04dd2d6154d97836b1f41ff06ffd278eb

guix/git-download.scm

@@ -115,12 +115,6 @@
   (define gnutls
     (module-ref (resolve-interface '(gnu packages tls)) 'guile-gnutls))
 
-  (define glibc-locales
-    ;; Note: pick the '-final' variant to avoid circular dependency on
-    ;; i586-gnu, where 'glibc-utf8-locales' indirectly depends on Git.
-    (module-ref (resolve-interface '(gnu packages commencement))
-                'glibc-utf8-locales-final))
-
   (define modules
     (delete '(guix config)
             (source-module-closure '((guix build git)
@@ -145,9 +139,7 @@
           ;; Let Guile interpret file names as UTF-8, otherwise
           ;; 'delete-file-recursively' might fail to delete all of
           ;; '.git'--see <https://issues.guix.gnu.org/54893>.
-          (setenv "GUIX_LOCPATH"
-                  #+(file-append glibc-locales "/lib/locale"))
-          (setlocale LC_ALL "en_US.utf8")
+          (setlocale LC_ALL "C.UTF-8")
 
           ;; The 'git submodule' commands expects Coreutils, sed, grep,
           ;; etc. to be in $PATH.  This also ensures that git extensions are