gnu: parted: Build against Readline 6.2.

* gnu/packages/readline.scm (readline-6.2): New variable.
* gnu/packages/parted.scm (parted): Use it instead of READLINE.

gnu/packages/parted.scm

@@ -53,7 +53,11 @@
     (inputs
      ;; XXX: add 'lvm2'.
      `(("check" ,check)
-       ("readline" ,readline)
+
+       ;; With Readline 6.3, parted/ui.c fails to build because it uses the
+       ;; now undefined 'CPPFunction' type.
+       ("readline" ,readline-6.2)
+
        ("util-linux" ,util-linux)))
     (native-inputs
      `(("gettext" ,gnu-gettext)))

gnu/packages/readline.scm

@@ -74,3 +74,14 @@ features both Emacs-like and vi-like keybindings, making its usage
 comfortable for anyone.")
       (license gpl3+)
       (home-page "http://savannah.gnu.org/projects/readline/"))))
+
+(define-public readline-6.2
+  (package (inherit readline)
+    (version "6.2")
+    (source (origin (inherit (package-source readline))
+              (method url-fetch)
+              (uri (string-append "mirror://gnu/readline/readline-"
+                                  version ".tar.gz"))
+              (sha256
+               (base32
+                "10ckm2bd2rkxhvdmj7nmbsylmihw0abwcsnxf8y27305183rd9kr"))))))