Provide a new Perl package 'cloc'. (#5525)

+ Count, or compute differences of, physical lines of source code in the
  given files (may be archives such as compressed tarballs or zip files)
  and/or recursively below the given directories.

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

@@ -0,0 +1,50 @@
+##############################################################################
+# Copyright (c) 2013-2017, 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 NOTICE and LICENSE files 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 Cloc(Package):
+    """Count, or compute differences of, physical lines of source code in the
+    given files (may be archives such as compressed tarballs or zip files)
+    and/or recursively below the given directories."""
+    homepage = "https://github.com/AlDanial/cloc/"
+    url      = "https://github.com/AlDanial/cloc/releases/download/1.74/cloc-1.74.tar.gz"
+
+    version('1.74', '1372da13a83862c186aa0b6b0c9b86f5')
+
+    depends_on('perl')
+
+    def install(self, spec, prefix):
+        # rewrite the script's #! line to call the perl dependency
+        shbang = '#!' + spec['perl'].command.path
+        filter_file(r'^#!/usr/bin/env perl', shbang, 'cloc')
+        filter_file(r'^#!/usr/bin/env perl', shbang, 'sqlite_formatter')
+
+        # cloc doesn't have a build system. We have to do our own install here.
+        mkdirp(prefix.bin)
+        install('cloc', join_path(prefix.bin, "cloc"))
+        install('sqlite_formatter', join_path(prefix.bin, "sqlite_formatter"))
+        install('./LICENSE', "%s" % prefix)
+        install('./README.md', "%s" % prefix)