bisect--helper: make the order consistently `argc, argv`

bisect--helper: make the order consistently `argc, argv`

In C, the natural order is for `argc` to come before `argv` by virtue of
the `main()` function declaring the parameters in precisely that order.

It is confusing & distracting, then, when readers familiar with the C
language read code where that order is switched around.

Let's just change the order and avoid that type of developer friction.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>