Install directories mode 755 instead of using umask Problem reported by Antoine Amarilli in: https://lists.gnu.org/archive/html/automake/2019-01/msg00000.html and followed up by Akim Demaille in: https://lists.gnu.org/archive/html/bug-bison/2020-07/msg00040.html * bin/automake.in: Add a comment about this. * lib/install-sh: Ignore umask; just create directories mode 755 unless overridden via -m (for non-intermediate directories only). Also, fix 'umask=$mkdir_umask' typo. * lib/mkinstalldirs: Likewise.