Makefile: don't perform "mv $@+ $@" dance for $(GENERATED_H)

Makefile: don't perform "mv $@+ $@" dance for $(GENERATED_H)

Change the "cmd.sh > $@+ && mv $@+ $@" pattern used for generating the
config-list.h and command-list.h to just "cmd.sh >$@". This was needed
as a guard to ensure that we don't have an empty file if the script
failed, but since 7b76d6bf221 (Makefile: add and use the
".DELETE_ON_ERROR" flag, 2021-06-29) GNU make ensures that doesn't
happen.

There's still a lot of other places in the Makefile where we
needlessly use this pattern, but I'm just changing these because I'm
about to add a new $(GENERATED_H) target, let's have them all look and
act the same way.

Even with ".DELETE_ON_ERROR" there is still a point to using the "mv
$@+ $@" pattern in some cases, e.g. to ensure that you have a working
binary during recompilation (see [1] for the start of a long
discussion about that), but that doesn't apply here. Nothing external
uses $(GENERATED_H) directly, it's only ever used in the context of
the Makefile's own dependency (re-)generation.

1. https://lore.kernel.org/git/8735t93h0u.fsf@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>