Add gawk (GNU awk) (#2625)

* Add gawk, GNU awk.

* flake8 fix.

var/spack/repos/builtin/packages/gawk/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 Gawk(AutotoolsPackage):
+    """If you are like many computer users, you would frequently like to make
+       changes in various text files wherever certain patterns appear, or
+       extract data from parts of certain lines while discarding the
+       rest. To write a program to do this in a language such as C or
+       Pascal is a time-consuming inconvenience that may take many lines
+       of code. The job is easy with awk, especially the GNU
+       implementation: gawk.
+
+       The awk utility interprets a special-purpose programming language
+       that makes it possible to handle simple data-reformatting jobs
+       with just a few lines of code.
+    """
+
+    homepage = "https://www.gnu.org/software/gawk/"
+    url      = "http://ftp.gnu.org/gnu/gawk/gawk-4.1.4.tar.xz"
+
+    version('4.1.4', '4e7dbc81163e60fd4f0b52496e7542c9')