gnu: orc: Use 'modify-phases'.

* gnu/packages/gstreamer.scm (orc)[arguments]: Use the 'modify-phases'
syntax.

gnu/packages/gstreamer.scm

@@ -72,9 +72,10 @@
                (base32
                 "0jd69ynvr3k70mlxxgbsk047l1rd63m1wkj3qdcq7644xy0gllkx"))))
     (build-system gnu-build-system)
-    (arguments `(#:phases
-                 (alist-cons-before
-                  'check 'disable-faulty-test
+    (arguments
+     `(#:phases
+       (modify-phases %standard-phases
+         (add-before 'check 'disable-faulty-test
            (lambda _
              ;; XXX Disable the 'test-limits' and 'exec_opcodes_sys'
              ;; tests, which fail on some machines.  See:
@@ -82,8 +83,7 @@
              (substitute* '("testsuite/test-limits.c"
                             "testsuite/exec_opcodes_sys.c")
                (("if \\(error\\) return 1;")
-                       "if (error) return 77;")))
-                  %standard-phases)))
+                "if (error) return 77;")))))))
     (home-page "http://code.entropywave.com/orc/")
     (synopsis "Oil runtime compiler")
     (description