pre-commit hook tests: don't leave "actual" nonexisting on failure

Start by creating an "actual" file in a core.hooksPath test that has the hook echoing to the "actual" file. We later test_cmp that file to see what hooks were run. If we fail to run our hook(s) we'll have an empty list of hooks for the test_cmp instead of a nonexisting file. For the logic of this test that makes more sense. See 867ad08a261 (hooks: allow customizing where the hook directory is, 2016-05-04) for the commit that added these tests. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>