Merge branch 'master' into ng/master

Merge branch 'master' into ng/master

* master:
  NEWS: fix typo
  NEWS: report recent documentation fix about AM_PROG_MKDIR_P
  NEWS: Automake 2.0 will assume "rm -f" without args work
  NEWS: on assuming "rm -f" without arguments work
  NEWS: fix a couple of typos in older entries
  docs: AM_PROG_MKDIR_P: will not be removed in 2.0 release of Automake
  docs: AM_PROG_CC_C_O: correct imprecise statements about it
  maint: sanity checks in 'check-minimal-autoconf' convenience target
  maint: test minimal supported autoconf through convenience target
  maint: install minimal supported autoconf through convenience targets
  test-lib: typofix in comments