Add GNU patch to Spack. (#2598)

var/spack/repos/builtin/packages/patch/package.py

+##############################################################################
+# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+from spack import *
+
+
+class Patch(AutotoolsPackage):
+    """Patch takes a patch file containing a difference listing produced by
+    the diff program and applies those differences to one or more
+    original files, producing patched versions.
+    """
+
+    homepage = "http://savannah.gnu.org/projects/patch/"
+    url      = "http://ftp.gnu.org/gnu/patch/patch-2.7.5.tar.xz"
+
+    version('2.7.5', 'e3da7940431633fb65a01b91d3b7a27a')