automake 1.16i

dist: more forcefully deal with mode 0 directories created by tests.

From https://bugs.gnu.org/67868.

* lib/am/distdir.am (am__remove_distdir): make directories
readable and searchable, not just writable. (Also typo.)
* t/local.mk (clean-local-check): ensure directories are
at least mode 700
* t/uninstall-fail.sh: restore reasonable permissions of
the mode 0 $inst/share directory at the end.