lint/gitconfig: Enable checkpatch.pl checking of commits

This patch enables running the checkpatch script on the code portion
of each commit as part of the pre-commit hook. At this point there
is no checking of the commit message in place (e.g. for typos)

Change-Id: I7cdf0692cf372986e411f4aba4691417b73c7511
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/8419
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>

util/gitconfig/pre-commit

@@ -1,2 +1,3 @@
 #!/bin/sh
-exec %MAKE% lint-stable
+%MAKE% lint-stable
+git diff --cached | util/lint/checkpatch.pl --no-signoff -q -

util/lint/lint-006-checkpatch

@@ -0,0 +1,23 @@
+#!/bin/sh
+# This file is part of the coreboot project.
+#
+# Copyright 2015 Google Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# 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
+# GNU General Public License for more details.
+#
+# DESCR: Checkpatch on all .c and .h files in the tree
+
+LC_ALL=C export LC_ALL
+util/lint/checkpatch.pl --show-types --file $( git ls-files \*.[ch] | \
+	grep -v ^payloads/libpayload/util/kconfig | \
+	grep -v ^payloads/libpayload/curses/PDCurses-3.4 | \
+	grep -v ^payloads/coreinfo/util/kconfig | \
+	grep -v ^util/kconfig \
+	)