gnu: Use the 'patches' field of <origin>.

* gnu/packages/apr.scm,
  gnu/packages/autotools.scm,
  gnu/packages/avahi.scm,
  gnu/packages/cdrom.scm,
  gnu/packages/cmake.scm,
  gnu/packages/cpio.scm,
  gnu/packages/cross-base.scm,
  gnu/packages/emacs.scm,
  gnu/packages/flex.scm,
  gnu/packages/fontutils.scm,
  gnu/packages/glib.scm,
  gnu/packages/grub.scm,
  gnu/packages/guile.scm,
  gnu/packages/idutils.scm,
  gnu/packages/libevent.scm,
  gnu/packages/linux.scm,
  gnu/packages/mail.scm,
  gnu/packages/make-bootstrap.scm,
  gnu/packages/mp3.scm,
  gnu/packages/oggvorbis.scm,
  gnu/packages/pdf.scm,
  gnu/packages/plotutils.scm,
  gnu/packages/qemu.scm,
  gnu/packages/recutils.scm,
  gnu/packages/rush.scm,
  gnu/packages/scheme.scm,
  gnu/packages/system.scm,
  gnu/packages/tcsh.scm,
  gnu/packages/valgrind.scm,
  gnu/packages/vpn.scm,
  gnu/packages/w3m: Use the 'patches' field of <origin> instead of
  adding a patch as input plus using #:patches.

gnu/packages/cross-base.scm

@@ -74,6 +74,9 @@ GCC that does not target a libc; otherwise, target that libc."
     (name (string-append "gcc-cross-"
                          (if libc "" "sans-libc-")
                          target))
+    (source (origin (inherit (package-source gcc-4.7))
+              (patches
+               (list (search-patch "gcc-cross-environment-variables.patch")))))
     (arguments
      `(#:implicit-inputs? #f
        #:modules ((guix build gnu-build-system)
@@ -81,7 +84,6 @@ GCC that does not target a libc; otherwise, target that libc."
                   (ice-9 regex)
                   (srfi srfi-1)
                   (srfi srfi-26))
-       #:patches (list (assoc-ref %build-inputs "patch/cross-env-vars"))
 
        ,@(substitute-keyword-arguments (package-arguments gcc-4.7)
            ((#:configure-flags flags)
@@ -177,10 +179,7 @@ GCC that does not target a libc; otherwise, target that libc."
             #f))))
 
     (native-inputs
-     `(("patch/cross-env-vars"
-        ,(search-patch "gcc-cross-environment-variables.patch"))
-
-       ("binutils-cross" ,xbinutils)
+     `(("binutils-cross" ,xbinutils)
 
        ;; Call it differently so that the builder can check whether the "libc"
        ;; input is #f.