use gnumakefile and maintainer-makefile modules from gnulib

* bootstrap (modules): Add gnumakefile and maintainer-makefile.
* GNUmakefile: Remove file, now provided by gnulib.
* Makefile.maint: Remove.  Replaced by maint.mk from gnulib.
.gitignore: Add GNUmakefile and maint.mk.
* cfg.mk (prev_version_file): Disable this feature.
Setting this to /dev/null avoids an otherwise harmless diagnostic.

.gitignore

@@ -35,3 +35,5 @@ stamp-h.in
 stamp-h1
 update.log
 tests/*.log
+/GNUmakefile
+/maint.mk

GNUmakefile

-# Having a separate GNUmakefile lets me `include' the dynamically
-# generated rules created via Makefile.maint as well as Makefile.maint itself.
-# This makefile is used only if you run GNU Make.
-# It is necessary if you want to build targets usually of interest
-# only to the maintainer.
-
-# Copyright (C) 2001, 2003, 2006-2009 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/>.
-
-# Systems where /bin/sh is not the default shell need this.  The $(shell)
-# command below won't work with e.g. stock DOS/Windows shells.
-ifeq ($(wildcard /bin/s[h]),/bin/sh)
-SHELL = /bin/sh
-else
-# will be used only with the next shell-test line, then overwritten
-# by a configured-in value
-SHELL = sh
-endif
-
-_have-Makefile := $(shell test -f Makefile && echo yes)
-
-# If the user runs GNU make but has not yet run ./configure,
-# give them a diagnostic.
-ifeq ($(_have-Makefile),yes)
-
-# Make tar archive easier to reproduce.
-export TAR_OPTIONS = --owner=0 --group=0 --numeric-owner
-
-include Makefile
-
-include $(srcdir)/cfg.mk
-include $(srcdir)/Makefile.maint
-
-else
-
-all:
-	@echo There seems to be no Makefile in this directory.   1>&2
-	@echo "You must run ./configure before running \`make'." 1>&2
-	@exit 1
-
-check dist distcheck install: all
-
-endif
-
-# Tell version 3.79 and up of GNU make to not build goals in this
-# directory in parallel.  This is necessary in case someone tries to
-# build multiple targets on one command line.
-.NOTPARALLEL:

bootstrap

@@ -78,8 +78,10 @@ getaddrinfo
 gethostname
 getpass
 gettext
+gnumakefile
 inet_pton
 ioctl
+maintainer-makefile
 mkstemp
 mktempd
 perror

cfg.mk

@@ -227,3 +227,6 @@ sc_libvirt_unmarked_diagnostics:
 	   | grep '[	 ]"' &&						\
 	  { echo '$(ME): found unmarked diagnostic(s)' 1>&2;		\
 	    exit 1; } || :
+
+# We don't use this feature of maint.mk.
+prev_version_file = /dev/null