Makefile: correct the dependency graph of hook-list.h

Makefile: correct the dependency graph of hook-list.h

Fix an issue in my cfe853e66be (hook-list.h: add a generated list of
hooks, like config-list.h, 2021-09-26), the builtin/help.c was
inadvertently made to depend on hook-list.h, but it's used by
builtin/bugreport.c.

The hook.c also does not depend on hook-list.h. It did in an earlier
version of the greater series cfe853e66be was extracted from, but not
anymore. We might end up needing that line again, but let's remove it
for now.

Reported-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>