gnu: Remove glibc@2.21 and its traces.

* gnu/packages/base.scm (glibc-2.21): Remove.
* gnu/system/locale.scm (localedef-command)[maybe-version-directory]:
Remove.  Replace call with use of 'package-version'.
(single-locale-directory): Remove 'version>=' conditional.

gnu/packages/base.scm

@@ -978,23 +978,11 @@ GLIBC/HURD for a Hurd host"
          `(modify-phases ,phases
             (add-before 'configure 'fix-pwd
               (lambda _
-                ;; Use `pwd' instead of `/bin/pwd' for glibc-2.21
+                ;; Use `pwd' instead of `/bin/pwd' for glibc-2.22.
                 (substitute* "configure"
                   (("/bin/pwd") "pwd"))
                 #t))))))))
 
-(define-public glibc-2.21
-  (package
-    (inherit glibc-2.22)
-    (version "2.21")
-    (source (origin
-              (inherit (package-source glibc-2.22))
-              (uri (string-append "mirror://gnu/glibc/glibc-"
-                                  version ".tar.xz"))
-              (sha256
-               (base32
-                "1f135546j34s9bfkydmx2nhh9vwxlx60jldi80zmsnln6wj3dsxf"))))))
-
 (define-public glibc-locales
   (package
     (inherit glibc)

gnu/system/locale.scm

@@ -22,7 +22,6 @@
   #:use-module (guix monads)
   #:use-module (guix records)
   #:use-module (guix packages)
-  #:use-module (guix utils)
   #:use-module (gnu packages base)
   #:use-module (gnu packages compression)
   #:use-module (srfi srfi-26)
@@ -85,15 +84,6 @@ or #f on failure."
 (define* (localedef-command locale
                             #:key (libc (canonical-package glibc)))
   "Return a gexp that runs 'localedef' from LIBC to build LOCALE."
-  (define (maybe-version-directory)
-    ;; XXX: For libc prior to 2.22, GuixSD did not store locale data in a
-    ;; version-specific sub-directory.  Check whether this is the case.
-    ;; TODO: Remove this hack once libc 2.21 is buried.
-    (let ((version (package-version libc)))
-      (if (version>=? version "2.22")
-          (list version "/")
-          '())))
-
   #~(begin
       (format #t "building locale '~a'...~%"
               #$(locale-definition-name locale))
@@ -102,7 +92,7 @@ or #f on failure."
                       "-i" #$(locale-definition-source locale)
                       "-f" #$(locale-definition-charset locale)
                       (string-append #$output "/"
-                                     #$@(maybe-version-directory)
+                                     #$(package-version libc) "/"
                                      #$(locale-definition-name locale))))))
 
 (define* (single-locale-directory locales
@@ -119,12 +109,7 @@ of LIBC."
     #~(begin
         (mkdir #$output)
 
-        ;; XXX: For libcs < 2.22, locale data is stored in the top-level
-        ;; directory.
-        ;; TODO: Remove this hack once libc 2.21 is buried.
-        #$(if (version>=? version "2.22")
-              #~(mkdir (string-append #$output "/" #$version))
-              #~(symlink "." (string-append #$output "/" #$version)))
+        (mkdir (string-append #$output "/" #$version))
 
         ;; 'localedef' executes 'gzip' to access compressed locale sources.
         (setenv "PATH" (string-append #$gzip "/bin"))