t: check that a pattern without trailing slash matches a directory

Prior to v1.8.1.1, with: git init echo content >foo && mkdir subdir && echo content >subdir/bar && echo "subdir export-ignore" >.gitattributes git add . && git commit -m one && git archive HEAD | tar tf - the resulting archive would contain only "foo" and ".gitattributes", not subdir. This was broken with a recent change that intended to allow "subdir/ export-ignore" to also exclude the directory, but instead ended up _requiring_ the trailing slash by mistake. A pattern "subdir" should match any path "subdir", whether it is a directory or a non-directory. A pattern "subdir/" insists that a path "subdir" must be a directory for it to match. This patch adds test not just for this simple case, but also for deeper cross-directory cases, as well as cases with wildcards. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>