Add framework for code style- and syntax-checking rules.

Almost all tests are initially disabled via the list in Makefile.cfg.
	* Makefile.am (EXTRA_DIST): Add .x-sc_avoid_if_before_free.
	Omit names of files that automake includes automatically.
	* .x-sc_avoid_if_before_free: New file.
	* build-aux/vc-list-files: Likewise.
	* build-aux/find-unnecessary-if-before-free: Likewise.
	* GNUmakefile, Makefile.cfg, Makefile.maint: New files.

build-aux/vc-list-files

@@ -0,0 +1,50 @@
+#!/bin/sh
+# List the specified version-controlled files.
+
+# Copyright (C) 2006, 2007 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/>.
+
+
+# List the specified version-controlled files.
+# With no argument, list them all.
+# This script must be run solely from the top of a $srcdir build directory.
+
+# If there's an argument, it must be a single, "."-relative directory name.
+# cvsu is part of the cvsutils package: http://www.red-bean.com/cvsutils/
+
+dir=
+case $# in
+  0) ;;
+  1) dir=$1 ;;
+  *) echo "$0: too many arguments" 1>&2; exit 1 ;;
+esac
+
+test "x$dir" = x && dir=.
+
+if test -d CVS; then
+  if test -x build-aux/cvsu; then
+    build-aux/cvsu --find --types=AFGM "$dir"
+  else
+    awk -F/ '{				\
+	if (!$1 && $3 !~ /^-/) {	\
+	  f=FILENAME;			\
+	  sub(/CVS\/Entries/, "", f);	\
+	  print f $2;			\
+	}}'				\
+      $(find ${*-*} -name Entries -print) /dev/null;
+  fi
+else
+  git-ls-files "$dir"
+fi