maint: arrange for the sc_require_config_h_first test to pass

* cfg.mk: New file, to configure maint.mk.
* Makefile.am (EXTRA_DIST): Add, so the new file is distributed.
(config_h_header): Define, to make the sc_require_config_h_first
syntax-check test pass.
* pc/chdirsaf.c: Include <config.h>.

Makefile.am

@@ -22,6 +22,7 @@ SUBDIRS = lib src tests
 dist_man1_MANS = patch.man
 EXTRA_DIST = \
 	ChangeLog-2011 \
+	cfg.mk \
 	m4/mkdir.m4 \
 	m4/setmode.m4 \
 	m4/utimbuf.m4 \

cfg.mk

@@ -0,0 +1,21 @@
+# Customize maint.mk                           -*- makefile -*-
+# Copyright (C) 2011 Free Software Foundation, 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, either version 3 of the License, or
+# (at your option) any later version.
+
+# 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.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+config_h_header = <(common|config)\.h>
+
+update-copyright-env = \
+  UPDATE_COPYRIGHT_USE_INTERVALS=1 \
+  UPDATE_COPYRIGHT_MAX_LINE_LENGTH=79

pc/chdirsaf.c

@@ -1,6 +1,7 @@
 /* A safer version of chdir, which returns back to the
    initial working directory when the program exits.  */
 
+#include <config.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>