build: fix 'make check' with newer git

Newer git doesn't like the maint.mk rule 'public-submodule-commit'
run during 'make check', as inherited from our checkout of gnulib.
I tracked down that libvirt commit 8531301d picked up a gnulib fix
that makes git happy.  Rather than try and do a full .gnulib
submodule update to gnulib.git d18d1b802 (as used in that libvirt
commit), it was easier to just backport the fixed maint.mk from
gnulib on top of our existing submodule level.  I did it as follows,
where these steps will have to be repeated when cherry-picking this
commit to any other maintenance branch:

mkdir -p gnulib/local/top
cd .gnulib
git checkout d18d1b802 top/maint.mk
git diff HEAD > ../gnulib/local/top/maint.mk.diff
git reset --hard
cd ..
git add gnulib/local/top
Signed-off-by: NEric Blake <eblake@redhat.com>

gnulib/local/top/maint.mk.diff

+diff --git c/top/maint.mk w/top/maint.mk
+index e52deb4..d5bb427 100644
+--- c/top/maint.mk
++++ w/top/maint.mk
+@@ -2,7 +2,7 @@
+ # This Makefile fragment tries to be general-purpose enough to be
+ # used by many projects via the gnulib maintainer-makefile module.
+
+-## Copyright (C) 2001-2012 Free Software Foundation, Inc.
++## Copyright (C) 2001-2014 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
+@@ -155,7 +155,7 @@ export LC_ALL = C
+ ## Sanity checks.  ##
+ ## --------------- ##
+
+-_cfg_mk := $(shell test -f $(srcdir)/cfg.mk && echo '$(srcdir)/cfg.mk')
++_cfg_mk := $(wildcard $(srcdir)/cfg.mk)
+
+ # Collect the names of rules starting with 'sc_'.
+ syntax-check-rules := $(sort $(shell sed -n 's/^\(sc_[a-zA-Z0-9_-]*\):.*/\1/p' \
+@@ -591,7 +591,7 @@ sc_prohibit_root_dev_ino_without_use:
+
+ sc_prohibit_openat_without_use:
+ 	@h='openat.h' \
+-	re='\<(openat_(permissive|needs_fchdir|(save|restore)_fail)|l?(stat|ch(own|mod))at|(euid)?accessat)\>' \
++	re='\<(openat_(permissive|needs_fchdir|(save|restore)_fail)|l?(stat|ch(own|mod))at|(euid)?accessat|(FCHMOD|FCHOWN|STAT)AT_INLINE)\>' \
+ 	  $(_sc_header_without_use)
+
+ # Prohibit the inclusion of c-ctype.h without an actual use.
+@@ -809,7 +809,7 @@ sc_prohibit_always_true_header_tests:
+ 	  $(_sc_search_regexp)
+
+ sc_prohibit_defined_have_decl_tests:
+-	@prohibit='#[	 ]*if(n?def|.*\<defined)\>[	 (]+HAVE_DECL_'	\
++	@prohibit='(#[	 ]*ifn?def|\<defined)\>[	 (]+HAVE_DECL_'	\
+ 	halt='HAVE_DECL macros are always defined'			\
+ 	  $(_sc_search_regexp)
+
+@@ -1121,9 +1121,11 @@ fix_po_file_diag = \
+ 'you have changed the set of files with translatable diagnostics;\n\
+ apply the above patch\n'
+
+-# Verify that all source files using _() are listed in po/POTFILES.in.
++# Verify that all source files using _() (more specifically, files that
++# match $(_gl_translatable_string_re)) are listed in po/POTFILES.in.
+ po_file ?= $(srcdir)/po/POTFILES.in
+ generated_files ?= $(srcdir)/lib/*.[ch]
++_gl_translatable_string_re ?= \b(N?_|gettext *)\([^)"]*("|$$)
+ sc_po_check:
+ 	@if test -f $(po_file); then					\
+ 	  grep -E -v '^(#|$$)' $(po_file)				\
+@@ -1143,7 +1145,7 @@ sc_po_check:
+ 	    esac;							\
+ 	    files="$$files $$file";					\
+ 	  done;								\
+-	  grep -E -l '\b(N?_|gettext *)\([^)"]*("|$$)' $$files		\
++	  grep -E -l '$(_gl_translatable_string_re)' $$files		\
+ 	    | sed 's|^$(_dot_escaped_srcdir)/||' | sort -u > $@-2;	\
+ 	  diff -u -L $(po_file) -L $(po_file) $@-1 $@-2			\
+ 	    || { printf '$(ME): '$(fix_po_file_diag) 1>&2; exit 1; };	\
+@@ -1281,15 +1283,17 @@ vc-diff-check:
+ rel-files = $(DIST_ARCHIVES)
+
+ gnulib_dir ?= $(srcdir)/gnulib
+-gnulib-version = $$(cd $(gnulib_dir) && git describe)
++gnulib-version = $$(cd $(gnulib_dir)				\
++                    && { git describe || git rev-parse --short=10 HEAD; } )
+ bootstrap-tools ?= autoconf,automake,gnulib
+
++gpgv = $$(gpgv2 --version >/dev/null && echo gpgv2 || echo gpgv)
+ # If it's not already specified, derive the GPG key ID from
+ # the signed tag we've just applied to mark this release.
+ gpg_key_ID ?=								\
+   $$(cd $(srcdir)							\
+      && git cat-file tag v$(VERSION)					\
+-        | gpgv --status-fd 1 --keyring /dev/null - - 2>/dev/null	\
++        | $(gpgv) --status-fd 1 --keyring /dev/null - - 2>/dev/null	\
+         | awk '/^\[GNUPG:\] ERRSIG / {print $$3; exit}')
+
+ translation_project_ ?= coordinator@translationproject.org
+@@ -1313,7 +1317,7 @@ announcement_mail_Cc_ ?= $(announcement_mail_Cc_$(release-type))
+ announcement_mail_headers_ ?= $(announcement_mail_headers_$(release-type))
+ announcement: NEWS ChangeLog $(rel-files)
+ # Not $(AM_V_GEN) since the output of this command serves as
+-# annoucement message: it would start with " GEN announcement".
++# announcement message: it would start with " GEN announcement".
+ 	$(AM_V_at)$(srcdir)/$(_build-aux)/announce-gen			\
+ 	    --mail-headers='$(announcement_mail_headers_)'		\
+ 	    --release-type=$(release-type)				\
+@@ -1368,7 +1372,8 @@ endef
+
+ .PHONY: no-submodule-changes
+ no-submodule-changes:
+-	$(AM_V_GEN)if test -d $(srcdir)/.git; then			\
++	$(AM_V_GEN)if test -d $(srcdir)/.git				\
++		&& git --version >/dev/null 2>&1; then			\
+ 	  diff=$$(cd $(srcdir) && git submodule -q foreach		\
+ 		  git diff-index --name-only HEAD)			\
+ 	    || exit 1;							\
+@@ -1386,10 +1391,12 @@ submodule-checks ?= no-submodule-changes public-submodule-commit
+ # cannot be built from a fresh clone.
+ .PHONY: public-submodule-commit
+ public-submodule-commit:
+-	$(AM_V_GEN)if test -d $(srcdir)/.git; then			\
++	$(AM_V_GEN)if test -d $(srcdir)/.git				\
++		&& git --version >/dev/null 2>&1; then			\
+ 	  cd $(srcdir) &&						\
+-	  git submodule --quiet foreach test '$$(git rev-parse $$sha1)'	\
+-	      = '$$(git merge-base origin $$sha1)'			\
++	  git submodule --quiet foreach					\
++	      'test "$$(git rev-parse "$$sha1")"			\
++		  = "$$(git merge-base origin "$$sha1")"'		\
+ 	    || { echo '$(ME): found non-public submodule commit' >&2;	\
+ 		 exit 1; };						\
+ 	else								\
+@@ -1419,6 +1426,7 @@ alpha beta stable: $(local-check) writable-files $(submodule-checks)
+ 	$(AM_V_at)$(MAKE) -s emit_upload_commands RELEASE_TYPE=$@
+
+ release:
++	$(AM_V_GEN)$(MAKE) _version
+ 	$(AM_V_GEN)$(MAKE) $(release-type)
+
+ # Override this in cfg.mk if you follow different procedures.