gnu: shaderc: Update to 2018.0.

* gnu/packages/vulkan.scm (shaderc): Update to 2018.0.

gnu/packages/vulkan.scm

@@ -275,21 +275,19 @@ API.")
     (license (list license:asl2.0)))) ;LICENSE.txt
 
 (define-public shaderc
-  (let ((commit "be8e0879750303a1de09385465d6b20ecb8b380d")
-        (revision "2"))
   (package
     (name "shaderc")
-      (version (git-version "0.0.0" revision commit))
+    (version "2018.0")
     (source
      (origin
        (method git-fetch)
        (uri (git-reference
              (url "https://github.com/google/shaderc")
-               (commit commit)))
-         (file-name (string-append name "-" version ".tar.gz"))
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
         (base32
-           "16p25ry2i4zrj00zihfpf210f8xd7g398ffbw25igvi9mbn4nbfd"))))
+         "0qigmj0riw43pgjn5f6kpvk72fajssz1lc2aiqib5qvmj9rqq3hl"))))
     (build-system meson-build-system)
     (arguments
      `(#:tests? #f ; FIXME: Tests fail.
@@ -343,7 +341,7 @@ API.")
     (synopsis "Tools for shader compilation")
     (description "Shaderc is a collection of tools, libraries, and tests for
 shader compilation.")
-      (license license:asl2.0))))
+    (license license:asl2.0)))
 
 (define-public vkd3d
   (let ((commit "ecda316ef54d70bf1b3e860755241bb75873e53f")) ; Release 1.1.