tests: avoid spurious failure when 'install-info' program is unavailable From a report by Dmitry V. Levin: <http://lists.gnu.org/archive/html/automake-patches/2012-04/msg00085.html> * t/install-info-dir.sh : When 'install-info' is unavailable, create a dummy '${infodir}/dir' file by hand when that file is required by later checks. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>