gnu: s2tc: Fetch sources from git.

* gnu/packages/gl.scm (s2tc)[source]: Fetch from git.

gnu/packages/gl.scm

@@ -4,7 +4,7 @@
 ;;; Copyright © 2014, 2016 David Thompson <davet@gnu.org>
 ;;; Copyright © 2014, 2015, 2016, 2017 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2016 Nils Gillmann <ng0@n0.is>
-;;; Copyright © 2016, 2017 Ricardo Wurmus <rekado@elephly.net>
+;;; Copyright © 2016, 2017, 2018 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2016 David Thompson <davet@gnu.org>
 ;;; Copyright © 2017, 2018 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2017 Arun Isaac <arunisaac@systemreboot.net>
@@ -49,6 +49,7 @@
   #:use-module (gnu packages xml)
   #:use-module (gnu packages xorg)
   #:use-module (guix download)
+  #:use-module (guix git-download)
   #:use-module (guix build utils)
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system cmake)
@@ -177,12 +178,13 @@ Polygon meshes, and Extruded polygon meshes.")
     (version "1.0")
     (source
      (origin
-       (method url-fetch)
-       (uri (string-append
-             "https://github.com/divVerent/s2tc/archive/v" version ".tar.gz"))
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/divVerent/s2tc.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
-        (base32 "0ibfdib277fhbqvxzan0bmglwnsl1y1rw2g8skvz82l1sfmmn752"))
-       (file-name (string-append name "-" version ".tar.gz"))))
+        (base32 "1fg323fk7wlv2xh6lw66wswgcv6qi8aaadk7c28h2f2lj1s7njnf"))))
     (build-system gnu-build-system)
     (native-inputs
      `(("autoconf" ,autoconf)