Merge branch 'master' into ng/master

Merge branch 'master' into ng/master

* master:
  fixup: s/AM_CONFIG_HEADER/AC_CONFIG_HEADERS/ in 't/confsub.sh'
  tests: fix a spurious failure with dash
  test defs: fix indentation (cosmetic change)
  tests: remove obsolete uses of $sh_errexit_works
  configure: search a sturdy POSIX shell to be used in the testsuite
  tests: shell running test scripts is now named AM_TEST_RUNNER_SHELL
  fixup: distribute t/README
  init: warn against obsolete usage of AM_INIT_AUTOMAKE

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