gnu: gdk-pixbuf: Merge the two 'arguments' fields.

This is a followup to commit 0d5ddad.

* gnu/packages/gtk.scm (gdk-pixbuf): Merge the two 'arguments' fields.

gnu/packages/gtk.scm

@@ -335,7 +335,23 @@ printing and other features typical of a source code editor.")
               "062x2gqd7p6yxhxlib1ha4l3gk9ihcj080hrwwv9vmlmybb064hi"))))
    (build-system gnu-build-system)
    (arguments
-    '(#:configure-flags '("--with-x11")))
+    '(#:configure-flags '("--with-x11")
+      #:phases
+      (modify-phases %standard-phases
+        (add-after
+         'unpack 'disable-failing-tests
+         (lambda _
+           (substitute* "tests/Makefile.in"
+             ;; XXX FIXME: This test fails on some machines with:
+             ;; GLib-FATAL-ERROR: gmem.c:103: failed to allocate
+             ;; 6039798016 bytes
+             (("cve-2015-4491\\$\\(EXEEXT\\) ") "")
+             ;; XXX FIXME: This test fails with:
+             ;; ERROR:pixbuf-jpeg.c:74:test_type9_rotation_exif_tag:
+             ;; assertion failed (error == NULL): Data differ
+             ;; (gdk-pixbuf-error-quark, 0)
+             (("pixbuf-jpeg\\$\\(EXEEXT\\) ") ""))
+           #t)))))
    (propagated-inputs ; required by gdk-pixbuf-2.0.pc
     `(("glib" ,glib)
       ("libpng" ,libpng)))
@@ -347,22 +363,6 @@ printing and other features typical of a source code editor.")
      `(("pkg-config" ,pkg-config)
        ("glib" ,glib "bin")                               ; glib-mkenums, etc.
        ("gobject-introspection", gobject-introspection))) ; g-ir-compiler, etc.
-   (arguments
-    `(#:phases (modify-phases %standard-phases
-                 (add-after
-                  'unpack 'disable-failing-tests
-                  (lambda _
-                    (substitute* "tests/Makefile.in"
-                      ;; XXX FIXME: This test fails on some machines with:
-                      ;; GLib-FATAL-ERROR: gmem.c:103: failed to allocate
-                      ;; 6039798016 bytes
-                      (("cve-2015-4491\\$\\(EXEEXT\\) ") "")
-                      ;; XXX FIXME: This test fails with:
-                      ;; ERROR:pixbuf-jpeg.c:74:test_type9_rotation_exif_tag:
-                      ;; assertion failed (error == NULL): Data differ
-                      ;; (gdk-pixbuf-error-quark, 0)
-                      (("pixbuf-jpeg\\$\\(EXEEXT\\) ") ""))
-                    #t)))))
    (synopsis "GNOME image loading and manipulation library")
    (description
     "GdkPixbuf is a library for image loading and manipulation developed