Merge branch 'master' into ng/master

Merge branch 'master' into ng/master

* master:
  docs: AM_CFLAGS: remove reference to non-existing "more detailed" desc
  maintcheck: prefer '$(am__cd)' over plain 'cd'
  fetch: improve, and reduce code duplication
  docs: add rule to generate manuals for www.gnu.org
  docs: copy the 'gendocs.sh' script from Texinfo CVS repository
  sync: update files from upstream with "make fetch"
  release: generate a stub for the release announcement
  release: distinguish major and minor releases
  tests: avoid two spurious failures on FreeBSD

+ Extra non-trivial changes:

* Makefile.am (clean_texinfo_clutter_cmd, clean-web-manuals): Simply
use "cd" rather than "$(am__cd)".

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>