gnu: cssc: Use 'modify-phases'.

* gnu/packages/version-control.scm (cssc)[arguments]: Use 'modify-phases'.

gnu/packages/version-control.scm

@@ -898,8 +898,9 @@ (define-public cssc
                                        "cssc-missing-include.patch"))))
     (build-system gnu-build-system)
     (arguments
-     `(#:phases (alist-cons-before
-                 'check 'precheck
+     `(#:phases
+       (modify-phases %standard-phases
+         (add-before 'check 'precheck
            (lambda _
              (begin
                (substitute* "tests/common/test-common"
@@ -913,8 +914,7 @@ (define-public cssc
                ;; not belong) in the /etc/group file of the build environment.
                ;; Currently we do not have such a group.  Disable this test for now.
                (substitute* "tests/Makefile"
-                       (("test-delta ") ""))))
-                 %standard-phases)))
+                 (("test-delta ") ""))))))))
     ;; These are needed for the tests
     (native-inputs `(("git" ,git)
                      ("cvs" ,cvs)))