Merge branch 'maint' into yacc-work

Merge branch 'maint' into yacc-work

* maint: (34 commits)
  tests: drop unnecessary requirement in 'subpkg.test'
  gitlog-to-changelog: new auxiliary script, synced from gnulib
  docs: "aclocal --install -I /abs/dir" actually copies files
  docs: fix node names for automake and aclocal invocations
  gitignore: use only one .gitignore file, in the top-level directory
  tests: one more fixlet for gettext macros requirement
  tests: fix handling of gettext macros requirement
  tests: fix failure due to debugging code forgotten into a test
  tests: avoid spurious failure of libtool and gettext tests
  hacking: distribute it, and mention it in the ChangeLog
  regex: deprecate the obsolete macro AM_WITH_REGEX
  maint: distribute .xz tarballs, not .bz2 ones
  maint: better use of autoconf 2.68 features
  cosmetics: use proper m4 quoting in configure.ac
  include: avoid "deleted .am file" problem
  tests: better handling of gettext and libtool requirements
  fix: typos and grammaros in comments of the new test
  tests: report useful system information in 'test-suite.log'
  python: remove relics for Python 1.5 support
  configure: remove extraneous 'eval's from AM_RUN_LOG invocations
  ...