maint: resync files from upstream

maint: resync files from upstream

'make syntax-check' complained about something that was already
fixed upstream in doc/standards.texi, so I ran 'make update', and
omitted lib/Autom4te as that still has some issues to be sorted out.

* GNUmakefile: Resync from upstream.
* build-aux/announce-gen: Likewise.
* build-aux/config.guess: Likewise.
* build-aux/config.sub: Likewise.
* build-aux/git-version-gen: Likewise.
* build-aux/gitlog-to-changelog: Likewise.
* build-aux/gnupload: Likewise.
* build-aux/move-if-change: Likewise.
* build-aux/texinfo.tex: Likewise.
* build-aux/update-copyright: Likewise.
* build-aux/useless-if-before-free: Likewise.
* build-aux/vc-list-files: Likewise.
* doc/gendocs_template: Likewise.
* doc/standards.texi: Likewise.
* m4/autobuild.m4: Likewise.
* maint.mk: Likewise.