maint: resync files from upstream

maint: resync files from upstream

The files in lib/Autom4te/ are intentionally not synced at this
point, since this recent Automake patch:
https://lists.gnu.org/archive/html/automake-patches/2012-03/msg00111.html

was buggy regarding '-' as stdout, and also exposes some latent
bugs in autoconf where we use raw 'open' instead of XFile::open.

* build-aux/announce-gen: Resync via 'make fetch'.
* build-aux/config.sub: Likewise.
* build-aux/git-version-gen: Likewise.
* build-aux/gnupload: Likewise.
* build-aux/move-if-change: Likewise.
* build-aux/texinfo.tex: Likewise.
* doc/standards.texi: Likewise.
* maint.mk: Likewise.