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.