gnu: font-liberation: Use 'font-build-system'.

* gnu/packages/fonts.scm (font-liberation): Switch to 'font-build-system'.

Signed-off-by: Arun Isaac <arunisaac@systemreboot.net>

gnu/packages/fonts.scm

@@ -231,34 +231,7 @@ sans-serif designed for on-screen reading.  It is used by GNOME@tie{}3.")
               (sha256
                (base32
                 "010m4zfqan4w04b6bs9pm3gapn9hsb18bmwwgp2p6y6idj52g43q"))))
-    (build-system trivial-build-system)
-    (arguments
-     `(#:modules ((guix build utils))
-       #:builder
-       (begin
-         (use-modules (guix build utils))
-
-         (let ((tar      (string-append (assoc-ref %build-inputs "tar")
-                                        "/bin/tar"))
-               (PATH     (string-append (assoc-ref %build-inputs "gzip")
-                                        "/bin"))
-               (font-dir (string-append %output "/share/fonts/truetype"))
-               (doc-dir  (string-append %output "/share/doc/" ,name)))
-           (setenv "PATH" PATH)
-           (system* tar "xvf" (assoc-ref %build-inputs "source"))
-           (mkdir-p font-dir)
-           (mkdir-p doc-dir)
-           (chdir (string-append "liberation-fonts-ttf-" ,version))
-           (for-each (lambda (ttf)
-                       (install-file ttf font-dir))
-                     (find-files "." "\\.ttf$"))
-           (for-each (lambda (doc)
-                       (install-file doc doc-dir))
-                     '("AUTHORS" "ChangeLog" "LICENSE" "README" "TODO"))))))
-    (native-inputs
-     `(("source" ,source)
-       ("tar" ,tar)
-       ("gzip" ,gzip)))
+    (build-system font-build-system)
     (home-page "https://pagure.io/liberation-fonts/")
     (synopsis
      "Fonts compatible with Arial, Times New Roman, and Courier New")