Merge branch 'micro' into maint

* micro:
  docs: AM_PROG_MKDIR_P: will not be removed in 2.0 release of Automake
  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

diff --cc .gitignore
Simple merge

diff --cc configure.ac
Simple merge

diff --cc doc/automake.texi
Simple merge

diff --cc maintainer/maint.mk
Simple merge

diff --cc t/ax/am-test-lib.sh
Simple merge