gnu: Remove 'guile-reader-for-guile_1.8'.

This was a useful example back in July 2012, but not very useful
beyond that.

* gnu/packages/guile.scm (guile-reader): Turn into a plain package.
  [source]: Use mirror:// URI.
  [inputs]: Use GUILE-2.0.
  [arguments]: Use the site/2.0 directory for --with-moduledir.
  (guile-reader/guile-1.8, guile-reader/guile-2.0): Remove.

gnu/packages/guile.scm

@@ -183,16 +183,13 @@ without requiring the source code to be rewritten.")
 ;;; Extensions.
 ;;;
 
-(define (guile-reader guile)
-  "Build Guile-Reader against GUILE, a package of some version of Guile 1.8
-or 2.0."
+(define-public guile-reader
   (package
-   (name (string-append "guile-reader-for-guile_" (package-version guile)))
+    (name "guile-reader")
     (version "0.6")
     (source  (origin
                (method url-fetch)
-             (uri (string-append
-                   "http://download-mirror.savannah.gnu.org/releases/guile-reader/guile-reader-"
+               (uri (string-append "mirror://savannah/guile-reader/guile-reader-"
                                    version ".tar.gz"))
                (sha256
                 (base32
@@ -200,14 +197,11 @@ or 2.0."
     (build-system gnu-build-system)
     (native-inputs `(("pkgconfig" ,pkg-config)
                      ("gperf" ,gperf)))
-   (inputs `(("guile" ,guile)))
+    (inputs `(("guile" ,guile-2.0)))
     (arguments `(#:configure-flags
                  (let ((out (assoc-ref %outputs "out")))
-                  ,(if (string-prefix? "2." (package-version guile))
-                       '(list (string-append "--with-guilemoduledir="
-                                             out "/share/guile/site/2.0"))
-                       '(list (string-append "--with-guilemoduledir="
-                                             out "/share/guile/site"))))))
+                   (list (string-append "--with-guilemoduledir="
+                                        out "/share/guile/site/2.0")))))
     (synopsis "Framework for building readers for GNU Guile")
     (description
      "Guile-Reader is a simple framework for building readers for GNU Guile.
@@ -224,14 +218,6 @@ many readers as needed).")
     (home-page "http://www.nongnu.org/guile-reader/")
     (license gpl3+)))
 
-(define-public guile-reader/guile-1.8
-  ;; Guile-Reader built against Guile 1.8.
-  (guile-reader guile-1.8))
-
-(define-public guile-reader/guile-2.0
-  ;; Guile-Reader built against Guile 2.0.
-  (guile-reader guile-2.0))
-
 (define-public guile-ncurses
   (package
     (name "guile-ncurses")