Add package for nginx@1.12.0 (#3810)

* Add package for nginx@1.12.0

Includes support for:
- zlib
- pcre (and pcre-jit)
- openssl (https support)

Built and basics tested on CentOS 7.  I haven't tested the `https`
support [yet].

* Include final bit of doc string sentence.

I trimmed the docstring that I lifed from https://nginx.org/en a bit
too aggressively and left a '...' to remind me to fix it.

Apparently I need more obvious reminders.

Thanks @davydden!

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

@@ -0,0 +1,44 @@
+##############################################################################
+# 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 Nginx(AutotoolsPackage):
+    """nginx [engine x] is an HTTP and reverse proxy server, a mail proxy
+    server, and a generic TCP/UDP proxy server, originally written by Igor
+    Sysoev."""
+
+    homepage = "https://nginx.org/en/"
+    url      = "https://nginx.org/download/nginx-1.12.0.tar.gz"
+
+    version('1.12.0', '995eb0a140455cf0cfc497e5bd7f94b3')
+
+    depends_on('openssl')
+    depends_on('pcre')
+    depends_on('zlib')
+
+    def configure_args(self):
+        args = ['--with-http_ssl_module']
+        return args